Title Details

Preface ix

Acknowledgements xi

1 Division, growth and differentiation of cells 1

The cell cycle 1

Mitosis 1

Meiosis 5

2 Gametogenesis 10

Spermatogenesis 10

Oogenesis 13

3 Fertilisation 17

Capacitation 18

Cellular events in the process of fertilisation 18

Barriers to polyspermy 18

Ovum activation 19

In vitro fertilisation 21

Comparative fertilisation rates 21

Sex determination 22

Parthenogenesis 22

Sex ratio 23

Chromosomes of domestic animals 23

4 Cleavage 25

Cleavage in primitive chordates, amphibians, avian species and mammals 25

Stem cells 30

5 Gastrulation 34

Primitive chordates 34

Amphibians 34

Avian species 34

Mammals 36

Establishment of left–right symmetry in vertebrates 38

Twinning 38

6 Aspects of cell signalling and gene functioning during development 42

Cellular messengers and receptors 42

Types of signalling 43

Induction and competence 44

Paracrine signalling during development 44

Apoptosis 48

Morphogens 49

Differentiation 49

Gene structure and organisation 49

X-chromosome inactivation 49

DNA methylation and parental imprinting in mammals 49

Promoters, enhancers and silencers 50

Transcription factors 50

Gene systems essential for development 50

Experimental measurement of gene expression 53

Experimental evaluation of gene function 53

Concluding comments 53

7 Establishment of the basic body plan 54

8 Coelomic cavities 59

Pleural and pericardial cavities 59

Diaphragm 61

Peritoneal cavity 64

Omenta 65

9 Foetal membranes 66

Development of the foetal membranes 68

Birds 68

Mammals 70

10 Forms of implantation and placentation 78

Implantation 78

Placentation in mammals 81

Functional aspects of the placenta 101

11 Cardiovascular system 105

Development of the cardiac tubes 106

Molecular aspects of cardiac development 112

Formation of the cardiac chambers 112

Conducting system of the heart 117

Developmental anomalies of the cardiovascular system 130

12 Embryological and post-natal features of haematopoiesis 136

Embryological aspects of haematopoiesis 136

Cell differentiation and maturation during haematopoiesis 139

Stem cells in human adults and mature animals 146

Immunodeficiency 147

Inherited defects in natural immunity 151

13 Nervous system 153

Dorsal–ventral patterning of the neural tube 153

Neural crest 154

Differentiation of the cellular components of the neural tube 155

Spinal nerves 157

Myelination of peripheral nerve fibres 161

Changes in the relative positions of the spinal cord and the developing vertebral column 161

Anomalies of the spinal cord 161

Differentiation of the brain sub-divisions 163

Ventricular system of the brain and cerebrospinal fluid circulation 174

Molecular aspects of brain development 175

Brain anomalies 176

Brain stem and spinal cord 177

Cranial nerves 178

Peripheral nervous system 178

Autonomic nervous system 178

Enteric nervous system 181

Meninges 182

14 Muscular and skeletal systems 184

Differentiation of somites 184

Muscular system 184

Skeletal muscle 184

Cytodifferentiation of muscle 186

Skeletal system 187

Skeletal anomalies 203

15 Digestive system 205

Molecular regulation of alimentary tract development 207

Oesophagus 209

Stomach 209

Liver 213

Pancreas 213

Spleen 216

Development and rotation of the intestines in domestic animals 217

Comparative features of the intestines 217

Hindgut 220

Developmental anomalies of the alimentary tract 221

16 Respiratory system 225

Formation of the larynx 225

Trachea, bronchi and lungs 225

Molecular aspects of respiratory development 231

Anomalies of the respiratory system 231

17 Urinary system 233

Kidney 233

Molecular basis of metanephros development 235

Unilobar kidneys 238

Multilobar kidneys 240

Bladder 240

Developmental anomalies of the urinary system 240

18 Male and female reproductive systems 244

Primordial germ cells 244

Undifferentiated stage of gonad formation 245

Differentiation and maturation of the testes 245

Differentiation and maturation of the ovaries 245

Features of equine gonadal development 248

Genital ducts 249

Formation of the genital fold 251

External genitalia 252

Factors which influence sexual differentiation in mammals 253

Sex determination 254

Molecular aspects of gonadogenesis 254

Influence of hormones on development of genital ducts and external genitalia 255

Sexual differentiation, associated brain function and subsequent sexual behaviour at puberty 257

Anomalies of sexual development 257

Descent of the testes 259

Ovarian migration 262

Cryptorchidism 262

Development of the mammary gland 263

Comparative features of mammary gland development in domestic animals 265

19 Structures in the head and neck 268

Pharyngeal region 268

Derivatives of the pharyngeal apparatus 269

Face 270

Nasal cavities 272

Oral cavity 277

Tongue 277

Salivary glands 278

Teeth 279

Comparative aspects of dentition 281

Molecular aspects of tooth development 282

Development of the skull 282

Congenital malformations of face and oral cavity 283

20 Endocrine system 286

Pituitary gland 286

Pineal gland 289

Adrenal glands 289

Thyroid gland 291

Parathyroid glands 291

Thymus 293

Pancreatic islets 293

21 Eye and ear 295

Eye 295

Ear 304

22 Integumentary system 313

Epidermis 313

Dermis 314

Hypodermis 315

Hair 315

Mammalian skin glands 318

Avian skin 320

Congenital and inherited defects of the skin 322

Hooves and claws 322

Horns and related structures 328

23 Age determination of the embryo and foetus 331

24 Genetic, chromosomal and environmental factors which adversely affect pre-natal development 337

Mutations 337

Chromosomal abnormalities 338

Teratogens 339

Therapeutic drugs and chemicals 339

Cytotoxic drugs used for treating neoplastic diseases 348

Poisonous plants 348

Infectious agents 349

Assessing the aetiology of congenital disease 353

Glossary 355

Index 364