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- Herausgeber: John Wiley & Sons
- Kategorie: Fachliteratur
- Sprache: Englisch
Veterinary Embryology, 2nd Edition, has been updated to reflect the many changes that have developed in the field; the text has been fully revised and expanded and is now in full colour and many pedagogical features and a companion website have been developed.
- A new edition of this highly successful student textbook, updated to reflect the latest developments in the field of embryology, with the inclusion of four new chapters
- Written by a team of authors with extensive experience of teaching this subject
- Short concise chapters on key topics describe complex concepts in a user-friendly way
- Additional tables, flow diagrams and numerous hand-drawn illustrations support the concepts presented in the text
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Seitenzahl: 1005
Veröffentlichungsjahr: 2017
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Table of Contents
Cover
Title Page
About the authors
Preface
Acknowledgements
About the companion website
How to access the website
Chapter 1: Historical aspects of embryology
Introduction
Dominant theories of generation in the seventeenth and eighteenth centuries
The origins of life
Contributions of the Ancient Greeks
The emergence of comparative embryology
The discovery of sperm
Experimental embryology
Evolutionary embryology
Genes and heredity
Creating life in vitro
Further reading
Chapter 2: Division, growth and differentiation of cells
The cell cycle
Mitosis
Meiosis
Further reading
Chapter 3: Gametogenesis
Spermatogenesis
Oogenesis
Further reading
Chapter 4: Fertilisation
Capacitation
Cellular events in the process of fertilisation
Barriers to polyspermy
Oocyte activation
Comparative fertilisation rates
Sex determination
Parthenogenesis
Sex ratio
Chromosomes of domestic animals
Further reading
Chapter 5: Cleavage
Cleavage in primitive chordates, amphibians, avian species and mammals
Further reading
Chapter 6: Gastrulation
Primitive chordates
Amphibians
Avian species
Mammals
Establishment of left–right symmetry in vertebrates
Twinning
Further reading
Chapter 7: Cell signalling and gene functioning during development
Types of signalling
Induction and competence
Cellular messengers and receptors
Paracrine and contact‐dependent signalling during embryological development
Apoptosis
Adhesion and migration
Morphogens
Gene structure and organisation
DNA methylation and parental imprinting in mammals
X‐chromosome inactivation
Histone modifications
Gene regulation
Transcription factors
Gene systems essential for development
Experimental measurement of gene expression
Experimental evaluation of gene function
Concluding comments
Further reading
Chapter 8: Stem cells
Stem cells in the embryo
Stem cells in adult mammals
Stem cells and embryological development
Induced pluripotent stem cells and their applications
Stem cells in domestic animals
Further reading
Chapter 9: Establishment of the basic body plan
Further reading
Chapter 10: Coelomic cavities
Pleural and pericardial cavities
Diaphragm
Peritoneal cavity
Omenta
Further reading
Chapter 11: Foetal membranes
Development of the foetal membranes
Avian species
Mammals
Further reading
Chapter 12: Forms of implantation and placentation
Implantation
Placentation in mammals
Functional aspects of the placenta
Further reading
Chapter 13: Embryo mortality in domestic species
Introduction
Establishment of pregnancy in cattle
Causes of embryonic mortality
Time of occurrence and incidence of embryo loss in cattle
Embryo mortality in sheep
Embryo mortality in pigs
Embryo mortality in horses
Embryo mortality in dogs
Embryo mortality in cats
Further reading
Chapter 14: Cardiovascular system
Development of the cardiac tubes
Molecular aspects of cardiac development
Formation of the cardiac chambers
Conducting system of the heart
Developmental anomalies of the cardiovascular system
Further reading
Chapter 15: Embryological and postnatal features of haematopoiesis
Ontogeny of haematopoiesis
Sites of haematopoiesis in the developing embryo
Cellular activity and other factors in the adult bone marrow which influence HSC development and activity
Acellular factors involved in haematopoiesis
Haematopoiesis in avian species
Immunodeficiency
Primary immunodeficiencies relating to innate immunity
Further reading
Chapter 16: Nervous system
Dorsal─ventral patterning of the neural tube
Neural crest
Differentiation of the cellular components of the neural tube
Spinal nerves
Myelination of peripheral nerve fibres
The final position of the spinal cord relative to the developing vertebral column
Anomalies of the spinal cord
Differentiation of the brain subdivisions
Ventricular system of the brain and cerebrospinal fluid circulation
Molecular aspects of brain development
Brain anomalies
Brain stem and spinal cord
Cranial nerves
Peripheral nervous system
Autonomic nervous system
Enteric nervous system
Meninges
Further reading
Chapter 17: Muscular and skeletal systems
Differentiation of somites
Muscular system
Skeletal muscle
Cytodifferentiation of muscle
Skeletal system
Skeletal anomalies
Further reading
Chapter 18: Digestive system
Molecular regulation of alimentary tract development
Oesophagus
Stomach
Liver
Pancreas
Spleen
Development and rotation of the intestines in domestic animals
Comparative features of the intestines
Hindgut
Developmental anomalies of the alimentary tract
Further reading
Chapter 19: Respiratory system
Formation of the larynx
Trachea, bronchi and lungs
Molecular aspects of respiratory development
Anomalies of the respiratory system
Further reading
Chapter 20: Urinary system
Kidney
Molecular basis of metanephros development
Unilobar kidneys
Multilobar kidneys
Bladder
Developmental anomalies of the urinary system
Further reading
Chapter 21: Male and female reproductive systems
Primordial germ cells
Undifferentiated stage of gonad formation
Differentiation and maturation of the testes
Differentiation and maturation of the ovaries
Features of equine gonadal development
Genital ducts
Formation of the genital fold
External genitalia
Factors which influence sexual differentiation in mammals
Molecular aspects of sexual differentiation and gonadogenesis
Influence of hormones on development of genital ducts and external genitalia
Sexual differentiation, associated brain function and subsequent sexual behaviour at puberty
Anomalies of sexual development
Descent of the testes
Ovarian migration
Cryptorchidism
Development of the mammary gland
Comparative features of mammary gland development in domestic animals
Further reading
Chapter 22: Structures in the head and neck
Pharyngeal region
Derivatives of the pharyngeal apparatus
Face
Nasal cavities
Oral cavity
Tongue
Salivary glands
Teeth
Comparative aspects of dentition
Molecular aspects of tooth development
Development of the skull
Congenital malformations of face and oral cavity
Further reading
Chapter 23: Endocrine system
Pituitary gland
Pineal gland
Adrenal glands
Thyroid gland
Parathyroid glands
Thymus
Pancreatic islets
Further reading
Chapter 24: Eye and ear
Eye
Ear
Further reading
Chapter 25: Integumentary system
Epidermis
Dermis
Hypodermis
Hair
Mammalian skin glands
Avian skin
Congenital and inherited defects of the skin
Hooves and claws
Horns and related structures
Further reading
Chapter 26: Age determination of the embryo and foetus
Further reading
Chapter 27: Assisted reproductive technologies used in domestic species
The impact of reproductive technologies on animal breeding
Assisted reproductive technologies in cattle
Assisted reproductive technologies in other domestic species
Further reading
Chapter 28: Genetic, chromosomal and environmental factors which adversely affect prenatal development
Mutations
Chromosomal abnormalities
Teratogens
Therapeutic drugs and chemicals
Poisonous plants
Infectious agents
Assessing the aetiology of congenital disease
Concluding comments
Further reading
Glossary
Useful websites
Index
End User License Agreement
List of Tables
Chapter 02
Table 2.1 The number of chromosomes in human and animal diploid cells.
Chapter 03
Table 3.1 Features of the oestrous cycle in domestic animals.
Chapter 04
Table 4.1 Volume of ejaculate, number of spermatozoa per ml, and site of deposition of spermatozoa in the female reproductive tract of domestic animals.
Table 4.2 Primary and secondary sex ratios per 100 individuals in humans and domestic animals.
Chapter 07
Table 7.1 The mediators of Shh signalling for
Drosophila
and mammals, their activity in mammalian species and the developmental consequences associated with defects in these signalling molecules or receptors.
Table 7.2 Major families of transcription factors and examples of their roles in vertebrate development.
Table 7.3 Genes within the homeotic complex of
Drosophila
species, their domains of expression and roles in development, based on data derived from mutant phenotypes.
Chapter 08
Table 8.1 Categories and characteristics of mammalian stem cells.
Chapter 11
Table 11.1 Incubation periods for some domesticated avian species.
Table 11.2 Umbilical cord lengths in domestic animals.
Chapter 12
Table 12.1 The interval between fertilisation and implantation in humans and in selected domestic animals.
Table 12.2 Description and histological classification of placentae of domestic animals, rodents and primates. Foetal layers are listed in accordance with their position relative to the maternal circulation.
Table 12.3 Days of pregnancy in particular species after which ovaries can be removed without inducing abortion.
Table 12.4 Transmission of passive immunity from dam to offspring.
Chapter 15
Table 15.1 Origin, lineage, distribution and other attributes of cells or formed elements produced during haematopoiesis or derived from blood cells in mammals.
Chapter 16
Table 16.1 Primary brain vesicles, brain subdivisions, their major derivatives and associated lumina.
Table 16.2 Functional roles of brain regions.
Table 16.3 Origin, functional role, associated ganglia and structures or regions served by the 12 cranial nerves.
Table 16.4 Nuclei of origin, associated ganglia and structures innervated by components of the parasympathetic division of the autonomic nervous system.
Chapter 19
Table 19.1 Duration, in gestational days, of the stages of lung development in humans and domestic animals.
Chapter 21
Table 21.1 Approximate times of commencement and completion of oogonial mitosis in domestic animals.
Table 21.2 Estimated germ cell numbers in the ovaries of developing bovine foetuses at different gestational ages.
Table 21.3 Approximate numbers of germ cells in canine ovaries from birth to 10 years of age.
Table 21.4 Embryonic primordia from which structures in the male and female reproductive systems arise.
Table 21.5 Times at which the major events in testicular descent occur in humans and in domestic animals. Numbers indicate days of gestation or days postpartum (dpp).
Chapter 22
Table 22.1 Derivatives of pharyngeal arches, pouches and clefts and their associated cranial nerves.
Table 22.2 Muscles in the head region which develop from somitomeres and somites and the cranial nerves which provide their innervation.
Chapter 26
Table 26.1 Time in days, estimated from ovulation, at which early stages of embryological development occur in domestic animals, from zygote formation to implantation.
Chapter 27
Table 27.1 Major developments in assisted reproductive technologies used in domestic animals from the eighteenth century onwards.
Table 27.2 The amount (%) by which the DNA content of an X‐bearing spermatozoon exceeds that of a Y‐bearing spermatozoon in different mammals.
Chapter 28
Table 28.1 Animal diseases or conditions which are attributed to dysfunction of a single gene.
Table 28.2 Important autosomal and sex‐linked conditions in humans due to chromosomal abnormalities.
Table 28.3 Chemicals, environmental pollutants, infectious agents, metabolic imbalances, physical factors, poisonous plants and therapeutic drugs implicated in the disruption of normal embryonic or foetal development through their teratogenic effects.
Table 28.4 Infectious agents implicated in bovine abortion.
Table 28.5 Infectious agents implicated in ovine abortion.
Table 28.6 Infectious agents implicated in porcine abortion.
Table 28.7 Infectious agents implicated in equine abortion.
Table 28.8 Infectious agents implicated in canine abortion.
Table 28.9 Infectious agents implicated in feline abortion or early embryonic death.
Table 28.10 Features of congenital diseases in animals which may assist in determining whether they are due to genetic or chromosomal factors or caused by teratogenic agents.
List of Illustrations
Chapter 01
Figure 1.1 The frontispiece of William Harvey’s
Exercitationes de generatione animalium
, published in 1651, showing Zeus liberating all living things from an egg bearing the inscription ‘
ex ovo omnia
’ (magnified on right).
Figure 1.2 Illustration of a homunculus in sperm, drawn by Nicolaas Hartsoeker, published as part of his 1694 French‐language paper entitled
Essai de Dioptrique
, a semi‐speculative work describing the potential new scientific observations that could be made using magnifying lenses.
Figure 1.3 Sperm from rabbits and dogs, drawn by Antonie van Leeuwenhoek. Published in
Philosophical Transactions
, the journal of the Royal Society, London, 1678.
Figure 1.4 Ernst Haeckel’s now discredited illustration of eight species compared at three stages of development. Left to right: fish, salamander, turtle, chicken, pig, cow, rabbit and human. From the second edition of
Anthropogenie
, published in 1874.
Figure 1.5 Timeline illustrating the contribution of key philosophers, scholars and scientists over two millennia to the gradual establishment of embryology as a progressive biological subject, not only in human but also in animal reproduction.
Chapter 02
Figure 2.1 Stages in somatic cell division indicating the major phases of the cell cycle.
Figure 2.2 An outline of the sequential stages in mitosis (A to G). After the G
2
phase, prophase commences, followed by metaphase, anaphase, telophase and cytokinesis, leading to the formation of two daughter cells.
Figure 2.3 Chiasma formation and reciprocal exchange of genetic material between non‐sister homologous chromatids during meiosis I.
Figure 2.4 An outline of the sequential stages of the first meiotic division (A to F) and second meiotic division (G to K). After the G
2
phase, during meiosis I, prophase I commences, followed by metaphase I, anaphase I and telophase I. Following meiosis I, prophase II commences, followed by metaphase II, anaphase II, and telophase II, leading to the formation of four haploid gametes. For clarity, only two pairs of chromosomes are represented.
Chapter 03
Figure 3.1 Stages in the development of spermatozoa from a primordial germ cell. Primordial germ cells, which remain dormant until puberty, differentiate into spermatogonia and, following meiosis, spermatozoa are formed from spermatids.
Figure 3.2 The morphological changes whereby a mammalian spermatid is converted into a spermatozoon.
Figure 3.3 Oogenesis, which begins in foetal life, is not completed until animals are sexually mature. Oocytes, gametes produced by female animals, provide the maternal genetic material and nourishment for the developing zygote.
Figure 3.4 Follicular development, ovulation, formation and regression of the corpus luteum in the mammalian ovary. Details of the released secondary oocyte and its associated structures are illustrated.
Chapter 04
Figure 4.1 Head of spermatozoon showing the structural changes which accompany the acrosome reaction (A to C).
Figure 4.2 Stages of fertilisation (A to G) including penetration of the corona radiata, binding to and penetration of the zona pellucida by the spermatozoon, contact of the spermatozoon with the vitelline membrane followed by the zona reaction, entry of the spermatozoon into the oocyte, formation and fusion of the pronuclei and formation of the zygote.
Figure 4.3 The chromosomal basis of sex determination in mammals.
Figure 4.4 The chromosomal basis of sex determination in avian species.
Chapter 05
Figure 5.1 Stages of cleavage from the 2‐cell stage to the early blastula stage in
Amphioxus
, A, and amphibians, B.
Figure 5.2 Stages of cleavage in the avian embryo from the first cleavage division to the formation of a blastoderm. Blastodisc viewed from above (left), and in cross‐section (right).
Figure 5.3 Stages of cleavage in a mammalian embryo from the two‐cell stage to the formation of a blastocyst.
Figure 5.4 Cross‐sections through mammalian blastocysts indicating the changes (A, B and C) involving Rauber’s layer and the formation of the embryonic disc and endoderm.
Chapter 06
Figure 6.1 Sections showing sequential stages of gastrulation in
Amphioxus
from the blastula stage A to the gastrula stage E. The section shown in E is at the level indicated in the embryo at the gastrula stage in F.
Figure 6.2 Sequential stages of gastrulation in amphibians from the blastula stage to the gastrula stage.
Figure 6.3 Stages of gastrulation in the chick embryo from the blastodisc to the formation of the primitive streak. Embryo viewed from a dorsal position (left) and with corresponding sections (right). Arrows indicate the direction of cellular migration.
Figure 6.4 The influence of the primitive node and notochord on the distribution of signalling and transcription factors associated with left–right symmetry.
Figure 6.5 Events during embryological development which result in the formation of monozygotic twins. A. Formation of two blastocysts within a single zona pellucida. B. Formation of two inner cell masses within a single blastocyst. C. Division of a blastocyst as it emerges from the zona pellucida.
Chapter 07
Figure 7.1 Cellular responses induced by extracellular signals. A. Cell division. B. Differentiation. C. Morphological change. D. Apoptosis.
Figure 7.2 Short‐range and long‐range signalling mechanisms. Short‐range mechanisms include A, paracrine signalling, B, contact‐dependent signalling, and C, autocrine signalling. Long‐range mechanisms include D, synaptic signalling and E, endocrine signalling.
Figure 7.3 The Hedgehog signalling transduction pathway illustrating the mechanisms of intracellular signalling in response to activation by the Hedgehog protein in A,
Drosophila
and B, mammals.
Figure 7.4 The fibroblast growth factor signal transduction pathway which operates through the phosphorylation of intracellular proteins, leading to their activation.
Figure 7.5 The Wingless signal transduction pathway, resulting in the activation of Wingless‐responsive genes.
Figure 7.6 The transforming growth factor signal transduction pathway leading to activation of Tgf‐β‐responsive genes via SMAD proteins.
Figure 7.7 A cell expressing an increased concentration of Notch receptor can progress towards a particular lineage while inhibiting the differentiation of an apposing cell along the same lineage (A to C).
Figure 7.8 The homeotic complex in
Drosophila
and the four murine Hox complexes. The alignment of the paralogous groups from each complex illustrates the evolutionary conservation of these gene sequences across species and the homology of genes in different complexes within the same animal.
Chapter 08
Figure 8.1 Outline of the growth and differentiation of pluripotent stem cells derived from the fertilised oocyte or alternatively by transfection of adult somatic cells.
Figure 8.2 Villus and associated crypt in the murine small intestine. As enterocytes mature, they migrate to the villus tip (left). After a short interval, mature enterocytes are shed into the intestinal lumen. Cell types present in the crypt include Paneth cells and crypt base columnar stem cells. Cellular interactions, niche factors and the prevailing microenvironmental conditions in the crypt promote replacement of enterocytes by crypt base columnar stem cells.
Figure 8.3 Bivalent domains can act either repressively or permissively in stem cells. In pluripotent stem cells, both repressive (H3K27me3) and permissive (H3K4me3) histone marks are present. Following exposure to appropriate signals, these marks can be reset to activate lineage‐specific genes or silence genes which are not required at a particular stage of differentiation.
Figure 8.4 Methods which can be used for induction of pluripotency in somatic cells and embryonic sources of cells, including germ cells, from which pluripotent cells can be recovered. Parthenogenesis is another method for producing totipotent stem cells, utilising the haploid oocyte and inducing it to develop to the blastocyst stage.
Chapter 09
Figure 9.1 Dorsal views and cross‐sections through an early mammalian embryo illustrating progressive developmental changes from formation of the primitive streak to neurulation (A to D).
Figure 9.2 Lateral views of a mammalian embryo at different stages of development showing recognisable structures.
Figure 9.3 The progressive differentiation of cells which arise from the blastocyst and form the three germ layers. Apart from primordial germ cells, all the cells, tissues and organs of the body are formed from these three germ layers.
Chapter 10
Figure 10.1 Cross‐sections through an embryo at an early stage of development showing formation of the intra‐embryonic coelom (A and B).
Figure 10.2 Dorsal views of a mammalian embryo at an early stage of development showing formation of the coelomic cavity (A to C).
Figure 10.3 Left lateral view of an embryo showing the arrangement of the pericardial and peritoneal cavities and the pericardial–peritoneal canal.
Figure 10.4 Sections through the thoracic region of an embryo at different stages of development, showing the formation of the pleural and pericardial cavities. In C, arrows indicate extension of pleural cavities into the body wall (A to D).
Figure 10.5 Sequential stages in the development of the diaphragm (A to C).
Figure 10.6 Cross‐sections through the abdominal region of embryos at different stages of development, at the level of the gut, A, B and C, and at the level of the stomach, D.
Chapter 11
Figure 11.1 A. Amphibian embryo with yolk stored within endodermal cells of ventral gut wall. B. Avian embryo with yolk stored as extra‐cellular ventral mass.
Figure 11.2 Formation of the trilaminar yolk sac in a chick embryo. Coelom formation resulting in the separation of the extra‐embryonic mesoderm into splanchnic and somatic layers.
Figure 11.3 Chick embryo showing folding of splanchnopleure and convergence of amniotic folds.
Figure 11.4 Chick embryo showing dorsal folding of the extra‐embryonic somatopleure, A. Fusion of the amniotic folds leading to the formation of outer chorionic and inner amniotic membranes, B.
Figure 11.5 Chick embryo showing enlargement of the allantois between the chorion and amnion and formation of amniotic duct.
Figure 11.6 Stages in the formation of a bilaminar yolk sac, A, and trilaminar yolk sac, B, in domestic animals. C. Formation of somatopleure and splanchnopleure. D. Convergence of amniotic folds and formation of definitive yolk sac.
Figure 11.7 A. The arrangement of the foetal membranes in domestic animals in early gestation. B. The arrangement of the foetal membranes in horses and carnivores as the chorioallantoic membrane enlarges to form the definitive placenta.
Figure 11.8 The foetal membranes in ruminants and pigs. Regression of the yolk sac is shown along with expansion of the chorioallantoic membrane.
Figure 11.9 Changes in the volumes of bovine foetal fluids at different stages of gestation.
Figure 11.10 The arrangement of the blood vessels and urachus in the porcine umbilical cord.
Chapter 12
Figure 12.1 Cross‐sections through pregnant uteri showing forms of implantation. A. Interstitial, anti‐mesometrial implantation. B. Interstitial, mesometrial implantation. C. Eccentric, anti‐mesometrial implantation. D. Centric or superficial implantation.
Figure 12.2 Cross‐sections through pregnant uteri showing orientation of blastocyst at time of implantation. A. Mesometrial orientation of inner cell mass. B. Anti‐mesometrial orientation of inner cell mass.
Figure 12.3 Components of a choriovitelline placenta and chorioallantoic placenta.
Figure 12.4 Classification of placentae based on the shape and the distribution of attachment sites of the chorion to the endometrium. A. Diffuse form of placentation which occurs in horses and pigs. B. Cotyledonary form of placentation which occurs in ruminants. C. Zonary form of placentation which occurs in carnivores. D. Discoidal form of placentation which occurs in humans, monkeys and rodents.
Figure 12.5 Classification of placentae based on the number of tissue layers interposed between foetal and maternal blood. A. Epitheliochorial. B. Synepitheliochorial. C. Endotheliochorial. D. Haemochorial.
Figure 12.6 Morphological changes in the porcine blastocyst showing the marked elongation which occurs between the 9th and 13th days of gestation, A to C. Enlarged view of the disc shows the primitive streak, primitive node and neural plate.
Figure 12.7 Spacing of porcine blastocysts A, and spacing of developing embryos enclosed in extra‐embryonic membranes B, within the uterus.
Figure 12.8 Arrangement of porcine foetal membranes
in utero
at day 30 of gestation showing anchor‐shaped allantois and avascular tips of the chorionic sac.
Figure 12.9 Porcine foetus enclosed within its amniotic sac which, in turn, is surrounded by its chorion. The avascular tips of the chorion and the chorionic portions of areolae are shown.
Figure 12.10 Microscopic appearance of porcine chorioallantoic placenta close to mid‐gestation illustrating the apposition of folded foetal and maternal epithelium and an areola.
Figure 12.11 Sequential changes in the developing bovine blastocyst and its location in the uterus from the third to the fourth week of gestation, showing the marked elongation of the blastocyst and its extension into the non‐pregnant horn (A to D).
Figure 12.12 Late stage in the process of implantation of a bovine foetus with clusters of chorionic villi interdigitating with maternal caruncles, forming placentomes.
Figure 12.13 Section through a bovine placentome, A, and ovine placentome, B, illustrating distinguishing features of these two specialised structures involved in maternal–foetal exchange. The bovine placentome is convex, whereas the ovine placentome is concave.
Figure 12.14 Microscopic appearance of bovine foetal–maternal placental interface illustrating the migration of binucleate trophoblastic cells into uterine epithelium.
Figure 12.15 Changes in the arrangement of equine foetal membranes from the 30th to the 70th day of gestation and the development of endometrial cups.
Figure 12.16 Microscopic appearance of equine foetal–maternal placental interface at mid‐pregnancy showing microcotyledons. Details of an individual microcotyledon are also shown (A and B).
Figure 12.17 Microscopic appearance of an equine endometrial cup, A, and details of cellular morphology and structures present, B.
Figure 12.18 A. Arrangement of canine foetal membranes within the uterus illustrating the zonary nature of chorioallantoic attachment to the endometrium and the position of haemophagous organs at the borders of the zonary region. B. Microscopic appearance of a section through the border of the zonary region of attachment.
Chapter 14
Figure 14.1 Outline of the origin and differentiation of angioblasts and haematopoietic stem cells from a common mesodermal precursor, the haemangioblast. The haematopoietic stem cell initially gives rise to a primitive erythroid lineage but as maturation proceeds definitive erythrocytes and myeloid cells are produced, along with cells from which the lymphoid lineage develops.
Figure 14.2 Sequential stages in the formation of blood vessels and blood cells from blood islands in the yolk sac (A to D).
Figure 14.3 Left lateral view of a mammalian embryo showing the rudimentary cardiovascular system.
Figure 14.4 Development of the cardiac tube and the coelomic cavity at the embryonic disc stage.
Figure 14.5 Sequential stages in the cranio‐caudal folding of the embryo showing the changed relationship of the developing heart to other embryonic structures (A to D). Arrows indicate the direction of folding of the embryo.
Figure 14.6 Stages in the formation of the heart from the cardiac tube stage to the development of an S‐shaped structure (A to I).
Figure 14.7 Ventral views of the developing cardiac tubes and coelom with corresponding cross‐sections (A to D).
Figure 14.8 Dorso‐ventral and left lateral views of sequential stages in the differentiation of the cardiac tube, from the bulbo‐ventricular loop stage to the expansion of the bulbo‐ventricular loop ventrally, and the common atrium dorsally (A to D).
Figure 14.9 Stages in the division of the common atrio‐ventricular canal into left and right atrio‐ventricular openings, resulting from the fusion of the endocardial cushions and the formation of the septum intermedium at the level of the endocardial cushions. Arrows in A and B indicate direction of growth of endocardial cushions; arrows in C indicate direction of blood flow.
Figure 14.10 Stages in the partitioning of the developing atrium and ventricle, leading to the formation of left and right atria and ventricles (A to F). The arrow in F indicates the direction of blood flow through the foramen ovale.
Figure 14.11 Incorporation of the sinus venosus into the right foetal atrium and incorporation of the pulmonary veins into the left foetal atrium.
Figure 14.12 Partitioning of the conus cordis and truncus arteriosus into the aortic and pulmonary trunks respectively. The spiral arrangement of the aortico‐pulmonary septum and the final relationship of the aortic and pulmonary trunks is also illustrated (A to C).
Figure 14.13 Stages in the closure of the inter‐ventricular foramen (A to C).
Figure 14.14 Sequential stages in the formation of the aortic valve. The valve of the pulmonary trunk forms in a similar manner (A to C).
Figure 14.15 Stages in the formation of an atrio‐ventricular valve, showing diverticulation of the ventricular musculature, formation of papillary muscles and attachment of chordae tendineae to valve cusps (A to C).
Figure 14.16 Illustration showing a ventral view, A, and a left lateral view, B, of the six pairs of aortic arch arteries. Although they develop sequentially, the illustration represents them as if they were present contemporaneously.
Figure 14.17 Ventral and left lateral views of the aortic arch arteries at an early stage of development, A, and at a later stage of development, B. Dotted lines indicate degenerating vessels.
Figure 14.18 Arrangement of the major blood vessels which arise from the arch of the aorta and the pulmonary trunk of domestic carnivores, A, and of horses and ruminants, B.
Figure 14.19 The initial relationships of the recurrent laryngeal nerves to the aortic arch arteries and their subsequent relationships to the blood vessels which arise from the aortic arch arteries.
Figure 14.20 Early (A) and late (B) stages in the formation of the vertebral, internal thoracic, subclavian and intercostal arteries. Vessels in A labelled 3, 4 and 6 are the aortic arch arteries which persist and from which definitive arteries arise.
Figure 14.21 The role of receptor–ligand interactions in fusion of arterial and venous endothelial cells.
Figure 14.22 Sequential stages in the differentiation of the vitelline and umbilical veins. During this differentiation, the hepatic sinusoids and the portal vein are formed (A to D).
Figure 14.23 Changes in the arrangement of the cardinal veins and their branches leading to the formation of the cranial vena cava and the caudal vena cava and their associated veins. Dotted lines denote structures which atrophy.
Figure 14.24 Outline of foetal circulation
in utero
. Arrows indicate the direction of blood flow.
Figure 14.25 Derivatives of germ layers from which cells, tissues, structures and organs of the cardiovascular system are formed. Structures in bold print are arranged alphabetically (based on Figure 9.3).
Figure 14.26 Changes in circulation which occur postnatally.
Figure 14.27 Outline of the developing lymphatic system, A and B, and the ducts draining lymph from regions of the embryo into the venous system, C.
Figure 14.28 Comparative structural features of a typical mammalian lymph node, A, and a porcine lymph node, B, illustrating the distribution of lymph nodules and the direction of lymph flow (arrows).
Figure 14.29 Sections through the heart showing normal anatomical arrangement, A. B. Patent ductus arteriosus. C and D. Pulmonary stenosis. E. Aortic stenosis. F. Tetralogy of Fallot. Arrows indicate direction of blood flow.
Figure 14.30 Sections through the heart showing an inter‐atrial defect, A, and an inter‐ventricular defect, B.
Figure 14.31 Ventral view of persistent right aortic arch with left ligamentum arteriosum, A. Left lateral view of the constriction of the oesophagus caused by left ligamentum arteriosum, B; cranial to the constriction, the oesophagus is dilated.
Figure 14.32 Ventral view of aberrant right subclavian artery.
Chapter 15
Figure 15.1 Extra‐embryonic and intra‐embryonic sites of haematopoiesis in mammals. Following migration to the foetal liver, haematopoietic stem cells (HSCs) move to the bone marrow. From these stem cells in the bone marrow, multipotent progenitor cells arise which are the source of myeloid and lymphoid cells, not only during foetal development but also throughout the animal’s life.
Figure 15.2 Outline of the tissues and structures, principally of mesodermal origin, associated with the formation of haematopoietic stem cells in mammals. Having reached their final destination, the bone marrow, these stem cells are the source of common myeloid progenitor cells and common lymphoid progenitor cells. Common myeloid progenitor cells are the source of myeloid blood cells and from common lymphoid progenitor cells B lymphocytes, T lymphocytes, natural killer cells and dendritic cells arise.
Figure 15.3 Origin of haematopoietic stem cells in mammals, leading to the production of common myeloid progenitor cells and common lymphoid progenitor cells. From these progenitor cells, progressive differentiation of committed cells leads to the production of mature blood cells and platelets. Some unresolved questions relating to the precise origin of basophils and eosinophils require further investigation. As blood cells differentiate, growth factors and microenvironmental factors strongly influence the lineage of individual cell types.
Figure 15.4 Timeline of extra‐embryonic and intra‐embryonic haematopoietic activity and the commencement of bone development associated with the murine embryo and foetus.
Figure 15.5 Origin, site of maturation and functional activity of lymphoid cells.
Figure 15.6 Origin, differentiation, maturation and functional activity of cells and formed elements which are derived from common myeloid progenitor cells in the bone marrow.
Figure 15.7 Sites in the chick embryo in which haematopoietic activity occurs at different times during incubation.
Figure 15.8 Anatomical structures, physiological activities, cells and secretions which cooperatively provide protection against infectious agents.
Figure 15.9 Causes of primary and secondary immunodeficiencies and components of the immune system affected.
Figure 15.10 Primary immunodeficiencies in humans and animals which result from congenital defects in lymphoid and myeloid cells and also in components of the complement system.
Chapter 16
Figure 16.1 Dorsal view of a developing embryo at the stage when neurulation commences.
Figure 16.2 Sections through the embryo at sequential stages of primary neurulation. A. Formation of the neural groove and location of neural crest cells. B. Formation of neural folds. C. Formation of the neural tube.
Figure 16.3 Dorsal—ventral patterning during formation of the neural tube.
Figure 16.4 Derivatives of cranial and spinal neural crest cells.
Figure 16.5 The origin and migratory pathways (arrows) of neural crest cells which arise from the thoraco‐lumbar region of the developing embryo, A. In their final location in the tissues, derivatives of these cells give rise to specialised cells and tissues, B.
Figure 16.6 Origin, differentiation and maturation of neurons, different types of glial cells and ependymal cells of the central nervous system.
Figure 16.7 Cross‐sections through the neural tube at different stages of formation of the spinal cord. A. The three layers of the neural tube. B. Formation of the alar and basal plates in the developing spinal cord. C. Fusion of the alar and basal plates which form the grey matter of the spinal cord.
Figure 16.8 Formation of a spinal nerve. Right side shows a motor axon growing out from a cell body in the ventral horn of the developing spinal cord innervating an effector organ. One process from a neuroblast in a spinal ganglion grows into the dorsal horn of the developing spinal cord while the other process terminates in a somatic sensory receptor. Left side shows a motor axon growing out from a cell body in the lateral horn of the developing spinal cord towards an autonomic ganglion. Subsequently, axons grow out from the neuroblasts in the autonomic ganglion and terminate in effector organs. One process from a neuroblast in a spinal ganglion grows into the dorsal horn of the developing spinal cord while the other process terminates in a visceral sensory receptor.
Figure 16.9 Section through the dorsal plane of the caudal end of the vertebral column showing the cauda equina and filum terminale.
Figure 16.10 Forms of spina bifida. A. Spina bifida occulta. B. Meningocoele. C. Meningomyelocoele. D. Myeloschisis and rachischisis resulting from failure of the neural tube to close and failure in the development of associated spinal structures.
Figure 16.11 Left lateral views and sections through the dorsal plane of the developing brain. A. The three primary brain vesicles. B. Cephalic flexure and cervical flexure and development of the telencephalon and diencephalon. C. Pontine flexure and development of the metencephalon and myelencephalon.
Figure 16.12 Cross section through the rostral portion of the myelencephalon showing the position of cranial nerve nuclei. Arrows indicate migration of cells from the alar plates to the olivary nucleus.
Figure 16.13 Dorsal view of the brain stem, showing positions of cranial nerve nuclei and columns within the brain stem. Nuclei and columns which develop in the basal plates are shown on the left; nuclei and columns which develop in the alar plates are shown on the right.
Figure 16.14 Dorsal view of the fourth ventricle after removal of the roof plate.
Figure 16.15 Dorsal views and cross‐sections at the levels indicated, through the myelencephalon, A, and the developing cerebellum and pons, B.
Figure 16.16 Dorsal view and longitudinal section of the developing cerebellum showing the commencement of surface folding.
Figure 16.17 Left lateral view and longitudinal section of the developing cerebellum showing marked folding of the surface, the formation of folia.
Figure 16.18 Section through the cerebellar cortex. Enlarged view shows the three definitive cellular layers of the cerebellar cortex.
Figure 16.19 Development of the basal and alar plates in the mesencephalon. Cross‐section through the mesencephalon at an early stage of development, A, and at a later stage of development, B, showing the alar and basal plates, the wide neural canal and migration of cells from the alar plates (arrows). C. Section through the mesencephalon showing the reduced size of the mesencephalic aqueduct and the development of motor and sensory nuclei from the basal and alar plates. The crura cerebri are also shown. Sections are at the levels indicated.
Figure 16.20 A. Median section through the forebrain showing the medial wall of the right cerebral hemisphere and the right thalamus and hypothalamus. B. Cross‐section through the forebrain at the level indicated, X, showing the lateral ventricles, the hippocampal lobes, the third ventricle and the choroid plexus.
Figure 16.21 A. Median section through the forebrain at a later stage than that shown in Figure 16.20A. B. Cross‐section through the forebrain at the level indicated, X. C. Cross section through the forebrain at the level indicated, Y.
Figure 16.22 A. Median section through the forebrain in the early foetal period showing the relationships of the developing brain structures. B. Cross‐section at the level indicated, X.
Figure 16.23 Median section through the embryonic brain, showing sequential stages in the development of structures of the forebrain and hindbrain. Arrows indicate direction of growth of the telencephalon.
Figure 16.24 Formation, circulation and drainage of cerebrospinal fluid in the cranial region, A. The relationships of the meninges to contiguous structures in the cranial region, B and in the spinal region, C. Arrows indicate direction of cerebrospinal fluid circulation.
Figure 16.25 Signalling patterns associated with the developing brain and rhombomeres.
Figure 16.26 Outline of the origin and distribution of the sympathetic nervous system, A, and the parasympathetic nervous system, B. Nerves shown as solid lines represent pre‐ganglionic fibres; nerves shown as broken lines represent post‐ganglionic fibres. Although nerves of both the sympathetic nervous system and the parasympathetic nervous system are bilateral in distribution, components of only one system are shown on each side.
Figure 16.27 Derivatives of germ layers from which cells, tissues, structures and organs of the nervous system are formed. Structures in bold print are arranged alphabetically (based on Figure 9.3).
Chapter 17
Figure 17.1 Cross‐sections through embryos at different stages of development showing structures which are derived from somites. A. Location of somites early in gestation. B. Formation of sclerotomes and dermomyotomes from somites. C. Separation of dermatome from myotome and formation of vertebral primordium. D. Division of myotomes into dorsal epimeres and ventral hypomeres. At this stage, innervation of both muscle masses by branches of spinal nerves occurs. E. Section through abdominal region showing the location of epaxial muscles which develop from epimeres and hypaxial muscles which are derived from hypomeres.
Figure 17.2 Stages in the formation of cartilage from mesenchymal cells (A to D).
Figure 17.3 Sequential stages in intramembranous ossification leading to the formation of a flat bone (A to D).
Figure 17.4 Longitudinal section through a long bone showing the distribution of cancellous bone and compact bone. The microscopic appearance of cancellous bone and compact bone is illustrated.
Figure 17.5 Sequential stages, A to E, in endochondral ossification leading to the formation of a long bone. The histological appearance of a region where calcified cartilage is replaced by bone is illustrated.
Figure 17.6 Sequential stages in the formation of vertebrae, associated musculature and intervertebral discs (A to F).
Figure 17.7 Location of centres of ossification which contribute to the formation of the body and arch of a typical vertebra. Costal ossification centres are also shown.
Figure 17.8 Stages in the formation of the porcine sternum, A to D. The dark areas in D represent centres of ossification.
Figure 17.9 Formation of fibrous, B, cartilaginous, C, and synovial, D, joints from a common mesenchymal structural outline, A.
Figure 17.10 Model for the specification of the proximo‐distal axis in limb bud development. A. The progress zone model. B. The early specification model. The numbers indicate zones of specification. In the progress zone model, A, it is proposed that cellular proliferation from the apical ectodermal ridge and also from the progress zone contributes to limb formation. The early specification model, B, proposes that cellular proliferation involving subsets of cells within three distinct zones is responsible for the development of the proximal, middle and distal regions of the limb.
Figure 17.11 The role of Hox gene expression in the specification of structures along the proximal–distal axis during the formation of a mammalian limb bud.
Figure 17.12 The major signalling factors in the limb bud associated with specification of digits. Arrows indicate positive influence of signalling molecules.
Figure 17.13 Derivatives of germ layers from which cells, tissues, structures and organs of the muscular and skeletal systems are formed. Structures in bold print are arranged alphabetically (based on Figure 9.3).
Chapter 18
Figure 18.1 Sequential stages in lateral body folding leading to the formation of the abdominal wall, the gut and its associated mesenteries. A. Cross‐section through an embryo prior to the formation of lateral body folds. B. Advanced stage of lateral body folding showing formation of the gut and the vitelline duct. C. Closure of the body wall and positions of the dorsal and ventral mesenteries. D. Atrophy of the ventral mesentery leading to formation of the peritoneal cavity.
Figure 18.2 Longitudinal sections through an embryo showing sequential stages in cranial and caudal body‐folding leading to the formation of the foregut, midgut and hindgut (A to C).
Figure 18.3 Regions of Hox gene expression in endodermally‐derived and mesodermally‐derived tissues along the cranial–caudal axis of the developing alimentary tract.
Figure 18.4 Lateral view A, and ventro‐lateral views and cross‐sections through the cranial abdominal region of a canine embryo. B. Developing stomach showing position of the dorsal mesogastrium and the ventral mesogastrium. C. Commencement of gastric rotation to the left and the position of the spleen in the dorsal mesogastrium and the liver in the ventral mesogastrium. D. Elongation of the dorsal mesogastrium and formation of the omental bursa. Growth of the liver in the ventral mesogastrium results in the formation of the lesser omentum dorsal to the liver and the falciform ligament ventrally.
Figure 18.5 Sequential stages in the formation of the four compartments of the ruminant stomach. A. Simple gastric primordium. B. Primordia of the rumen, reticulum, omasum and abomasum and formation of ruminal groove. C and D. Stages in caudal rotation of rumen. E. Final arrangement of the four compartments of the ruminant stomach.
Figure 18.6 Sequential stages in the development of the liver and pancreas (A to D).
Figure 18.7 Longitudinal section through the developing embryo showing the relationships of the mesenteries and associated structures.
Figure 18.8 Sequential stages in the development of the pancreas, A and B. Final arrangement of the pancreatic duct system in horses and dogs, C, in sheep, goats and cats, D, and in cattle and pigs, E.
Figure 18.9 Left lateral views showing stages in midgut rotation. A. Descending and ascending limbs of the midgut loop prior to rotation in direction of arrow. B. Change in relative positions of descending and ascending limbs of the midgut loop following initial stage of rotation. C. Further stage in midgut rotation. D. Final arrangement of limbs of the midgut loop in carnivores.
Figure 18.10 Anatomical arrangement of the large intestine of domestic animals showing comparative features of the caecum and ascending colon. A. Components of the large intestine in carnivores illustrating a simple ascending colon. B. Components of the large intestine of ruminants showing the coiled ascending colon positioned in a single plane. C. Components of porcine large intestine illustrating the cone‐shaped arrangement of the coiled ascending colon. D. Components of the equine large intestine illustrating the expanded caecum and enlarged ascending colon.
Figure 18.11 Stages in the development of the definitive equine caecum (A to D).
Figure 18.12 Longitudinal sections through the lumbo‐sacral region of an embryo showing stages in the division of the cloaca by the urorectal septum into the rectum and the urogenital sinus, A and B.
Figure 18.13 Derivatives of germ layers from which cells, tissues, structures and organs of the digestive system are formed. Structures in bold print are arranged alphabetically (based on Figure 9.3).
Figure 18.14 Stenosis and atresia of the small intestine. A. Normal intestine. B. Stenosis. C. Atresia. Cross‐sections of normal and abnormal intestines are shown.
Figure 18.15 Anomalies of the midgut loop and adjacent abdominal wall. A. Umbilical or vitelline fistula. B. Fibrous cord which is the remnant of the vitelline duct attaching the intestine to the abdominal wall. C. Cyst formation in the fibrous cord remnant of the vitelline duct. D. Meckel’s diverticulum.
Chapter 19
Figure 19.1 Lateral views, A, B, C and D and a ventral view, E, of sequential stages in the formation of the respiratory diverticulum from the foregut.
Figure 19.2 Ventral views of sequential stages in lung development showing the formation of the principal bronchi and the origins of lobar bronchi and their branches (A to C).
Figure 19.3 Structural changes which occur during stages of pulmonary development. A. Pseudoglandular stage. B. Canalicular stage. C. Terminal sac stage.
Figure 19.4 Dorsal views of the arrangement of lobar bronchi in the fully‐formed lungs of domestic animals (A to E). Lung lobation, as illustrated in this diagram, is based on the presence of a lobar bronchus supplying each lobe.
Figure 19.5 Derivatives of germ layers from which cells, tissues, structures and organs of the respiratory system are formed. Structures in bold print are arranged alphabetically (based on Figure 9.3).
Figure 19.6 Inductive influences of signalling factors on respiratory development. A. Outgrowth. B. Growth inhibition. C. Branching.
Chapter 20
Figure 20.1 Cross‐section, at the level indicated, through an early embryo, A, and an embryo at a later stage of development, B, showing formation of a pronephric duct and an internal and external glomerulus.
Figure 20.2 Cross‐sections through an embryo showing successive stages in the formation of a mesonephric tubule and paramesonephric duct.
Figure 20.3 Cross‐sections through embryos at the levels indicated, showing the formation of a mesonephric tubule and duct (A to C).
Figure 20.4 Stages in the formation of the pronephros, mesonephros and metanephros and their relationships to other developing structures (A to E).
Figure 20.5 Dorsal views of the developing pronephros, mesonephros and metanephros (A and B).
Figure 20.6 Stages in the formation of a nephron, its relationship to a collecting duct and its final arrangement in the functioning kidney (A to G).
Figure 20.7 Comparative features of kidneys of selected mammals. In aquatic mammals, fusion does not occur between adjacent renal lobes; the degree of fusion between adjacent renal lobes in domestic animals accounts for the gross anatomical appearance of their kidneys.
Figure 20.8 Sequential stages in the development of the bladder, ureters and associated structures.
Figure 20.9 Derivatives of germ layers from which cells, tissues, structures and organs of the urinary system are formed. Structures in bold print are arranged alphabetically (based on Figure 9.3).
Chapter 21
Figure 21.1 A. Route of migration of primordial germ cells from the allantois to the genital ridge, their site of differentiation. B. Transverse section through an embryo at the level indicated showing the migratory pathway of primordial germ cells along the dorsal mesentery to the genital ridge (arrows).
Figure 21.2 Sequential stages in the development of the undifferentiated gonad. A. Formation of sex cords in the genital ridge. B. Relationship between the mesonephric duct and the developing sex cords. C. Ventral view of the developing gonad shown in B.
Figure 21.3 Cross‐section A, and ventral view B, of the differentiation of the testis from the undifferentiated gonad, showing the formation of horseshoe‐shaped seminiferous cords. C. Cross‐section through seminiferous cords showing Sertoli cells, pre‐spermatogonia and interstitial cells.
Figure 21.4 Cross‐section A, and ventral view B, of differentiation of the ovary from the undifferentiated gonad, showing the formation of primordial follicles and the uterine tube. C. Primordial follicles.
Figure 21.5 Development of the undifferentiated genital duct systems, A, into the male duct system, B, and the female duct system, C.
Figure 21.6 Final anatomical arrangement of the reproductive tracts in selected mammals. The extent of paramesonephric duct fusion determines the shape of the body of the uterus and the nature of its relationship with the vagina. A. Rodent reproductive tract, showing a uterus duplex. B. Porcine reproductive tract, showing a bicornuate uterus. C. Primate reproductive tract, showing a uterus simplex.
Figure 21.7 Sequential stages in the development of the vagina (A to C).
Figure 21.8 Cross‐sections through a mammalian female embryo showing sequential stages in the formation of the genital fold.
Figure 21.9 Development of the male and female external genitalia. Undifferentiated stage of the external genitalia, A, and sequential stages in the development of the male external genitalia, B and C, and of the female external genitalia, D and E.
Figure 21.10 Closure of the urethral groove, A, and cross‐sections at different levels, B, showing progressive stages in the conversion of the urethral groove into a tube, the penile urethra.
Figure 21.11 Stages in the development of the terminal portion of the penile urethra (A to C).
Figure 21.12 Cellular and genetic interactions which specify development of the genital ridge, undifferentiated gonad and either a testis or ovary. Hormones subsequently secreted by the testis or ovary promote the development of a male or female duct system and associated external genitalia.
Figure 21.13 Derivatives of germ layers from which cells, tissues, structures and organs of the male reproductive system are formed. Structures in bold print are arranged alphabetically (based on Figure 9.3).
Figure 21.14 Derivatives of germ layers from which cells, tissues, structures and organs of the female reproductive system are formed. Structures in bold print are arranged alphabetically (based on Figure 9.3).
Figure 21.15 Stages in the descent of the bovine testis from a dorsal position in the peritoneal cavity, A, to a ventral location, B, and in its final position in the scrotum, C.
Figure 21.16 The position of the testis in the scrotum and the attachments of the three ligaments which are formed from the gubernaculum. The parietal layer of the tunica vaginalis has been reflected.
Figure 21.17 Sequential stages in the formation of the bovine mammary gland. A. Cross‐section through mammary crest. B. Cross‐section through mammary bud as the teat primordium is forming. C and D. Formation of primary sprout. E. Canalisation of primary sprout and formation of gland sinus. F. Formation of secondary sprouts from gland sinus. G. Canalisation of secondary sprouts.
Figure 21.18 Postnatal development of bovine mammary gland. A. Proliferation of lactiferous duct system and formation of suspensory apparatus of the mammary gland. B. Formation of alveolar secretory system.
Chapter 22
Figure 22.1 Position of pharyngeal arches in a developing mammalian embryo, A, and section through the pharyngeal region showing the pharyngeal arches, pouches and clefts, B.
Figure 22.2 Cervical sinus formed by proliferation of the second pharyngeal arch which overgrows the second and third pharyngeal clefts.
Figure 22.3 Sequential stages in the development of structures of the facial region of the pig (A to D).
Figure 22.4 Longitudinal sections through the cranial region of a developing embryo at the level of a nasal pit showing progressive development of the nasal and oral cavities (A to D).
Figure 22.5 Cross‐sections through the developing nasal and oral cavities showing the formation of the secondary palate, nasal septum and conchae (A to C).
Figure 22.6 Ventral views of the developing porcine palatine processes showing progressive formation of the secondary palate (A to D).
Figure 22.7 Longitudinal section through the equine head and cross‐section through the fully formed nasal and oral cavities showing prominent structures in this region.
Figure 22.8 A. Early stage in the development of the canine tongue, showing the major structures which contribute to its formation. B. Fully formed canine tongue.
Figure 22.9 Early stages in the formation of a deciduous brachyodont tooth, showing the development of the dental bud, dental cap and dental papilla and formation of the dental crown.
Figure 22.10 Final stage in the development and eruption of a deciduous brachyodont tooth, showing the structures which contribute to its formation.
Figure 22.11 Comparative features of an equine hypsodont incisor tooth, A, and a brachyodont incisor tooth from a dog, B.
Chapter 23
Figure 23.1 Sequential stages in the formation of the pituitary gland (A to E).
Figure 23.2 Relationships of the components of the fully‐formed porcine pituitary gland and histological features of the pars distalis, pars intermedia and pars nervosa, A; relationships of the components of the canine, equine, feline and bovine pituitary glands are shown in B, C, D and E respectively.
Figure 23.3 Stages in the formation of the adrenal gland. A. Migration of neural crest cells to the primordium of the adrenal cortex. B. Formation of adrenal medulla by neural crest cells. C. Fully formed adrenal gland showing the medulla, cortical zones and capsule.
Figure 23.4 Sequential stages in the formation of the thyroid and parathyroid glands, the thymus, palatine tonsil and associated structures. Details of the histological structure of the developing thyroid gland are shown.
Figure 23.5 Derivatives of germ layers from which cells, tissues, structures and organs of the endocrine system are formed. Structures in bold print are arranged alphabetically (based on Figure 9.3).
Chapter 24
Figure 24.1 Dorsal view of forebrain, A, prior to closure of the rostral neuropore showing the optic grooves, and a cross‐section, B, through the forebrain at the level of the optic grooves (X).
Figure 24.2 Developing forebrain showing the optic vesicles.
Figure 24.3 Cross‐section through forebrain at the level of the optic vesicles showing contact between the neuroepithelium of the optic vesicles and the surface ectoderm, A. Early stage in the formation of the optic cups and lens placodes, B.
Figure 24.4 Ventro‐lateral view of the optic cup and optic stalk showing the ventral choroid fissure.
Figure 24.5 Sequential stages in the closure of the choroid fissure in the optic stalk, showing the incorporation of the hyaloid vessels into the optic stalk and subsequent development of the optic nerve.
Figure 24.6 Sequential stages in the development of the lens vesicle and its invagination into the optic cup. A. Initial stage in the formation of the lens vesicle. B. Invagination of the lens vesicle into the optic cup. C. Longitudinal section through the optic stalk showing the position of the developing lens, which has lost contact with the surface ectoderm, within the optic cup.
Figure 24.7 Differentiation of the cells in the inner and outer walls of the optic cup. The position of the developing lens in relation to the optic cup and the early stages of eyelid formation are also shown.
Figure 24.8 Cross section through retina and associated structures showing cellular layers.
Figure 24.9 Section through the developing eye showing the relationships of its structures.
Figure 24.10 Developmental stages of iris, A and ciliary body, B.
Figure 24.11 Sequential stages in the formation of the lens. A. Formation of lens placodes from surface ectoderm. B and C. Stages in the invagination of the lens placodes leading to formation of the lens vesicle. D. Separation of the lens vesicle from the surface ectoderm. E. Elongation of cells in the posterior wall of the lens vesicle. F. Elimination of the cavity within the developing lens.
Figure 24.12 Stages in the development of the lacrimal apparatus.
Figure 24.13 Section through the fully developed eye.
Figure 24.14 Sections through the cranial region of an embryo at the level shown in A are presented in B, C and D at different stages of development, leading to the formation of the otic vesicles, E.
Figure 24.15 Stages in the formation of the membranous components of the inner ear. A. Development of the utricle and the saccule from the otic vesicle. B. Early stage in the formation of the semicircular ducts from the utricle and of the cochlear duct from the saccule. C and D. Intermediate stages in the formation of the semicircular ducts. E. Fully differentiated semicircular ducts. F. Membranous components of the inner ear.
Figure 24.16 Sequential stages in the formation of the structures of the inner ear. A. Cochlear duct surrounded by cartilage. B. Further development of the cochlear duct and associated structures. C. Formation of the scala tympani and scala vestibuli, the cochlear duct and the spiral ganglion in the osseous labyrinth.
Figure 24.17 Stages in the formation of the middle and external ear (A to C).
Figure 24.18 Cross‐section of the canine middle ear cavity showing its relationships to the external ear and inner ear.
Figure 24.19 Derivatives of germ layers from which cells, tissues, structures and organs of the eye and ear are formed. Structures in bold print are arranged alphabetically (based on Figure 9.3).
Chapter 25
Figure 25.1 Successive stages in the development of the epidermis and dermis. A. Ectoderm composed of a single layer of cells with underlying mesenchyme. B. Development of periderm. C. Formation of a multilayered epidermis. D. Foetal epidermis showing the formation of an epidermal peg. E. Development of the epidermis late in gestation showing the typical layers of stratified squamous epithelium.
Figure 25.2 Stages in the development of a simple hair follicle. A. Primordium of hair follicle. B. Hair bud. C. Bulbar stage of follicle formation. D. Projection of hair shaft from the follicle and formation of primordium of a sebaceous gland and a sweat gland. E. Mature hair follicle showing arrector pili muscle, sebaceous gland and apocrine sweat gland.
Figure 25.3 Compound hair follicle, which develops postnatally, showing the primary hair and associated secondary hairs.
Figure 25.4 Sequential stages in the hair cycle: anagen, catagen, telogen and commencement of a new anagen stage.
Figure 25.5 Stages in feather development. A. Early stage in the formation of a feather bud. B. Formation of a cone‐shaped dermal papilla. C. Feather bud projecting from the skin surface at the stage of follicle formation. D. Feather barbs projecting through broken sheath. E. Down feather. F. Early stage in cell proliferation from the epithelial collar of a feather follicle. G. Formation of barbs from a developing rachis. H. Circular arrangement of feather barbs before they assume a flat form. I. Contour feather.
Figure 25.6 Combined horizontal and vertical sections of the equine foot illustrating the anatomical relationships of its major components.
Figure 25.7 Palmar view of the left equine forelimb, A, and plantar view of the left equine hind limb, B, showing the positions of chestnuts and ergots.
Figure 25.8 Palmar view of the bovine forelimb, A, and porcine forelimb, B.
Figure 25.9 A. Lateral view of canine foot. B. Longitudinal section through the canine foot showing relationship of structures. C. Cross‐section through claw at the level indicated.
Figure 25.10 Palmar view of the canine right forelimb, A, and plantar view of the canine right hind limb, B.
Figure 25.11 Longitudinal section through a bovine horn.
Figure 25.12 Longitudinal section through velvet‐covered antler of a deer.
Figure 25.13 Derivatives of germ layers from which cells, tissues, structures and organs of the integumentary system are formed. Structures in bold print are arranged alphabetically (based on Figure 9.3).
Chapter 26
Figure 26.1 The relationship between crown–rump length and gestational age, measured from fertilisation, at given times during
in utero
development in equine, bovine, ovine and porcine species. These measurements, which are compiled from published reports, are influenced by breed differences, genetic factors and nutritional influences and are intended as a guide to age determination.
Figure 26.2 The relationship between crown–rump length and gestational age, measured from fertilisation, at given times during
in utero
development in canine and feline species. These measurements, which are compiled from published reports, are influenced by breed differences, genetic factors and nutritional influences and are intended as a guide to age determination.
Figure 26.3 The number of somite pairs observed at different gestational ages, measured from fertilisation, at given times during
in utero
development in equine, bovine, ovine and porcine species. To facilitate comparison of data, an arbitrary starting gestational age of 15 days has been selected for all species. These data, which are compiled from published sources, provide incomplete information on somite development.
Figure 26.4 The number of somite pairs observed at different gestational ages, measured from fertilisation, at given times during
in utero
development in canine and feline species. To facilitate comparison of data, an arbitrary starting gestational age of 15 days has been selected for both species. These data, which are compiled from published sources, provide incomplete information on somite development.
Figure 26.5 Developmental changes in equine, bovine and ovine embryos and foetuses. Measurements refer to approximate diameter of the blastocyst, the maximum length of the conceptus and the crown–rump length of the embryo. A number of structures which are readily recognisable are included.
Figure 26.6 Developmental changes in porcine, canine and feline embryos and foetuses. Measurements refer to approximate diameter of the blastocyst, the maximum length of the conceptus and the crown–rump length of the embryo. A number of structures which are readily recognisable are included.
Chapter 27
Figure 27.1 Reproductive technologies used to enhance genetic improvement.
Figure 27.2 Methods employed for the generation of multiple offspring from a valuable dam. MOET: multiple ovulation embryo transfer; AI: artificial insemination; IVF:
in vitro
fertilisation; NT: nuclear transfer.
Figure 27.3 Overview of multiple ovulation and embryo transfer in cattle. Following superovulation, the high genetic merit donor is inseminated with semen from a high genetic merit sire. Approximately seven days later, embryos are recovered by non‐surgical uterine flushing. Good quality embryos are transferred to synchronised recipients. Meanwhile, the valuable donor can be resynchronised and superovulated to produce more embryos, or she can be returned to natural breeding.
Figure 27.4
In vitro
production of embryos. This process involves maturation of immature oocytes recovered from the ovaries of slaughtered females or by transvaginal oocyte recovery from living animals. Matured oocytes are fertilised and the resulting embryos are cultured to the blastocyst stage, when they can be transferred to a recipient female or frozen for transfer at a future date.
Figure 27.5 Sex‐sorting of spermatozoa using flow cytometry.
Figure 27.6 Steps involved in the production of cloned embryos using nuclear transfer.
Chapter 28
Figure 28.1 Changes in the susceptibility of the embryo and foetus to teratogens at different stages of gestation.
Figure 28.2 The consequences of
in utero
infection with teratogenic viruses in domestic animals, which are determined by the stage of gestation at which infection is acquired.
Guide
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