Preface viii // Introduction / Embryology: Clinical Relevance and Historical Perspective xii // PARTI // General Embryology 01 // CHAPTER 1 I Introduction to Molecular Regulation and Signaling 3 // Gene Transcription 3 Other Regulators of Gene Expression 5 Induction and Organ Formation 5 Cell Signaling 6 // Key Signaling Pathways for Development 8 Summary 10 // CHAPTER 2 I Gametogenesis: Conversion of Germ Cells into Male and Female Gametes 14 // Primordial Germ Cells 14 The Chromosome Theory of Inheritance 15 Morphological Changes during Maturation of the Gametes 25 Summary 32 // CHAPTER 3 I First Week of Development: // Ovulation to Implantation 34 // Ovarian Cycle 34 // Fertilization 39 // Cleavage 42 // Blastocyst Formation 43 // Uterus at Time of Implantation 45 // Summary 47 // CHAPTER 4 I Second Week of Development: Bilaminar Germ Disc 49 // Day8 49 Day 9 50 Days 11 and 12 51 Day 13 52 Summary 56 // CHAPTER 5 I Third Week of Development: Trilaminar Germ Disc 58 // Gastrulation: Formation of Embryonic Mesoderm and Endoderm 58 Formation of the Notochord 58 Establishment of the Body Axes 59 Fate Map Established during Gastrulation 64 Growth of the Embryonic Disc 64 Further Development of the Trophoblast 67 Summary 68 // CHAPTER 6 I Third to Eighth Weeks: // The Embryonic Period 71 // Derivatives of the Ectodermal Germ Layer 71 Derivatives of the Mesodermal Germ Layer 78 Derivatives of the Endodermal Germ Layer 86 Patterning of the Anteroposterior Axis: // Regulation by Homeobox Genes 88 External Appearance during the Second Month 88 Summary 92 // CHAPTER 7 I The Gut Tube and the Body Cavities 95 // A Tube on Top of a Tube 95 Formation of the Body Cavity 96 Serous Membranes 96 Diaphragm and Thoracic Cavity 100 Formation of the Diaphragm 101 Summary 103 // CHAPTER 8 I Third Month to Birth: // The Fetus and Placenta 105 // Development of the Fetus 105 //
Fetal Membranes and Placenta 109 // Chorion Frondosum and Decidua Basalis 112 // Structure of the Placenta 112 // Amnion and Umbilical Cord 117 // Placental Changes at the End of Pregnancy 118 // Amniotic Fluid 118 // Fetal Membranes in Twins 120 // Parturition (Birth) 120 // Summary 125 // CHAPTER 9 I Birth Defects and Prenatal Diagnosis 126 // Birth Defects 126 Prenatal Diagnosis 136 Fetal Therapy 139 Summary 139 // PART 2 // Systems-Based Embryology 141 // CHAPTER 10 I The Axial Skeleton 143 // Skull 143 // Vertebrae and the Vertebral Column 152 Ribs and Sternum 154 Summary 155 // CHAPTER 11 I Muscular System 156 // Striated Skeletal Musculature 156 // Innervation of Axial Skeletal Muscles 157 // Skeletal Muscle and Tendons 159 // Molecular Regulation of Muscle Development 159 // Patterning of Muscles 159 // Head Musculature 159 // Limb Musculature 159 // Cardiac Muscle 160 // Smooth Muscle 160 // Summary 161 // CHAPTER 12 I Limbs 163 // Limb Growth and Development 163 Limb Musculature 166 Summary 174 // CHAPTER 13 I Cardiovascular System 175 // Establishment and Patterning of the Primary Heart Field 175 // Formation and Position of the Heart Tube 177 // Formation of the Cardiac Loop 179 // Molecular Regulation of Cardiac Development 182 // Contents // Development of the Sinus Venosus 183 // Formation of the Cardiae Septa 184 // Formation of the Conducting System of the Heart 201 // Vascular Development 202 // Circulation Before and After Birth 212 // Summary 215 // CHAPTER 14 I Respiratory System 218 // Formation of the Lung Buds 218 Larynx 220 // Trachea, Bronchi, and Lungs 220 Maturation of the Lungs 222 Summary 223 // CHAPTER 15 I Digestive System 225 // Divisions of the Gut Tube 225 Molecular Regulation of Gut Tube Development 226 Mesenteries 227 Foregut 228 // Molecular Regulation of Liver Induction 236 // Pancreas 238 // Midgut 239 // Hindgut 247 //
Summary 247 // CHAPTER 16 I Urogenital System 250 // Urinary System 250 Genital System 261 Summary 276 // CHAPTER 17 I Head and Neck 278 // Pharyngeal Arches 280 Pharyngeal Pouches 284 Pharyngeal Clefts 286 // Molecular Regulation of Facial Development 286 Tongue 291 Thyroid Gland 292 Face 292 // Intermaxillary Segment 296 Secondary Palate 297 Nasal Cavities 297 Teeth 302 // Molecular Regulation of Tooth Development 304 Summary 304 // CHAPTER 18 I Central Nervous System 306 // Spinal Cord 307 Brain 317 // Molecular Regulation of Brain Development 328 Cranial Nerves 334 Autonomic Nervous System 334 Summary 341 // CHAPTER 19 I Ear 343 // Internal Ear 343 Middle Ear 346 External Ear 348 Hearing 348 Summary 351 // CHAPTER 20 I Eye 352 // Optic Cup and Lens Vesicle 352 Retina, Iris, and Ciliary Body 354 Lens 355 // Choroid, Sclera, and Cornea 355 Vitreous Body 355 Optic Nerve 357 // Molecular Regulation of Eye Development 357 Summary 361 // CHAPTER 21 I Integumentary System 362 // Skin 362 Hair 364 // Fingernails and Toenails 365 Sweat Glands 365 Mammary Glands 365 Summary 367 // PART 3 // Appendix 369 // Answers to Problems 371 Figure Credits 382 Glossary of Key Terms 385 Index 395