Acquisitions Editor: Crystal Taylor Development Editor: Andrea Vosburgh Editorial Coordinator: Lauren Pecarich Production Product Manager: David Saltzberg Marketing Manager: Michael McMahon Manufacturing Coordinator: Margie Orzech Design Coordinator: Elaine Kasmer Compositor: Absolute Service. Inc.
I very student will be affected by pregnancy, either their mother,s, because what happens in the womb does not necessarily stay in the womb, or by someone else,s. As health care professionals, you will often encounter women of childbearing age who may be pregnant, or you may have children of your own, or maybe it is a friend who is pregnant. In any case, pregnancy and childbirth are relevant to all of us, and unfortunately, these processes often culminate in negative outcomes. For example, 50% of all embryos are spontaneously aborted. Furthermore, prematurity and birth defects are the leading causes of infant mortality and major contributors to disabilities. Fortunately, new strategies can improve pregnancy outcomes, and health care professionals have a major role to play in implementing these initiatives. However, a basic knowledge of embryology is essential to the success of these strategies, and with this knowledge, every health care professional can play a role in providing healthier babies.
Preface xi
Introduction / Embryology: Clinical Relevance and Historical Perspective xxi
Part 1 General Embryology 1
Chapter 1 Introduction to Molecular Regulation and Signaling 3
Gene Transcription 3
Other Regulators of Gene Expression 5
Induction and Organ Formation 6
Cell Signaling 6
Key Signaling Pathways for Development 8
Summary 10
Chapter 2 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 First Week of Development: Ovulation to Implantation 34
Ovarian Cycle 34
Fertilization 38
Cleavage 42
Blastocyst Formation 43
Epiblast, Hypoblast, and Axis Formation 44
Uterus at Time of Implantation 46
Summary 48
Chapter 4 Second Week of Development: Bilaminar Germ Disc 50
Day 8 50
Day 9 51
Days 11 and 12 52
Day 13 53
Summary 57
Chapter 5 Third Week of Development: Trilaminar Germ Disc 59
Gastrulation: Formation of Embryonic Mesoderm and Endoderm 59
Formation of the Notochord 59
Establishment of the Body Axes 60
Fate Map Established during Gastrulation 65
Growth of the Embryonic Disc 65
Further Development of the Trophoblast 68
Summary 69
Chapter б Third to Eighth Weeks: The Embryonic Period 72
Derivatives of the Ectodermal Germ Layer 72
Derivatives of the Mesodermal Germ Layer 80
Derivatives of the Endodermal Germ Layer 87
Patterning of the Anteroposterior Axis: Regulation by Homeobox Genes 89
External Appearance during the Second Month 90
Summary 93
Chapter 7 The Gut Tube and the Body Cavities 96
A Tube on Top of a Tube 96
Formation of the Body Cavity 97
Serous Membranes 97
Diaphragm and Thoracic Cavity 101
Formation of the Diaphragm 102
Summary 104
Chapter 8 Third Month to Birth: The Fetus and Placenta 106
Development of the Fetus 106
Fetal Membranes and Placenta 110
Chorion Frondosum and Decidua Basalis 113
Structure of the Placenta 113
Amnion and Umbilical Cord 118
Placental Changes at the End of Pregnancy 119
Amniotic Fluid 119
Fetal Membranes in Twins 121
Parturition (Birth) 121
Summary 126
Chapter 9 Birth Defects and Prenatal Diagnosis 128
Birth Defects 128
Prenatal Diagnosis 139
Fetal Therapy 143
Summary 143
Part 2 Systems-Based Embryology 145
Chapter TO The Axial Skeleton 147
Skull 147
Vertebrae and the Vertebral Column 156
Ribs and Sternum 158
Summary 159
Chapter 11 Muscular System 160
Striated Skeletal Musculature 160
Innervation of Axial Skeletal Muscles 161
Skeletal Muscle and Tendons 163
Molecular Regulation of Muscle Development 163
Patterning of Muscles 163
Head Musculature 163
Limb Musculature 163
Cardiac Muscle 164
Smooth Muscle 164
Summary 165
Chapter 12 Limbs 167
Limb Growth and Development 167
Limb Musculature 170
Summary 178
Chapter 13 Cardiovascular System 179
Establishment and Patterning of the Primary Heart Field 179
Formation and Position of the Heart Tube 181
Formation of the Cardiac Loop 183
Molecular Regulation of Cardiac Development 186
Development of the Sinus Venosus 187
Formation of the Cardiac Septa 188
Formation of the Conducting System of the Heart 205
Vascular Development 206
Circulation Before and After Birth 216
Summary 219
Chapter 14 Respiratory System 223
Formation of the Lung Buds 223
Larynx 225
Trachea, Bronchi, and Lungs 225
Maturation of the Lungs 227
Summary 228
Chapter 15 • Digestive System 230
Divisions of the Gut Tube 230
Molecular Regulation of Gut Tube Development 23 Mesentery 232 Foregut 233
Molecular Regulation of Liver Induction 242
Pancreas 244
Midgut 244
Hindgut 248
Summary 254
Chapter 16 Urogenital System 256
Urinary System 256
Genital System 267
Summary 282
Chapter 17 Head and Neck 284
Pharyngeal Arches 286
Pharyngeal Pouches 290
Pharyngeal Clefts 291
Molecular Regulation of Facial Development 292
Tongue 297
Thyroid Gland 298
Face 300
Intermaxillary Segment 301
Secondary Palate 301
Nasal Cavities 302
Teeth 302
Molecular Regulation of Tooth Development 310
Summary 311
Chapter 18 Central Nervous System 31: Spinal Cord 314
Brain 324
Molecular Regulation of Brain Development 336
Cranial Nerves 338
Autonomic Nervous System 342
Summary 349
Chapter 19 Ear 351
Internal Ear 351
Middle Ear 354
External Ear 356
Hearing 356
Summary 359
Chapter 20 Eye 360
Optic Cup and Lens Vesicle 360
Retina, Iris, and Ciliary Body 362
Lens 362
Choroid, Sclera, and Cornea 364
Vitreous Body 364
Optic Nerve 365
Molecular Regulation of Eye Development 365
Summary 369
Chapter 21 Integumentary System 370
Skin 370
Hair 372
Fingernails and Toenails 373
Sweat Glands 373
Mammary Glands 373
Summary 375
Part 3 Appendix 377
Answers to Problems 379
Figure Credits 391
Glossary of Key Terms 397
Index 411
