Introduction to Human Development 1
Developmental Periods 1
Stages of Embryonic Development 2
Postnatal Period 2
Infancy 2
Childhood 2
Puberty 2
Adulthood 4
Significance of Embryology 4
Historical Gleanings 4
Ancient Views of Human Embryology 4
Embryology in the Middle Ages 5
The Renaissance 5
Genetics and Human Development 7
Molecular Biology of Human Development 7
Human Blokinetlc Embryology 8
Descriptive Terms in Embiyology 8
Clinically Oriented Problems 8
First Week of Human Development 11
Garnet ogenesis 11
Meiosis 12
Spermatogenesis 12
Oogenesis 17
Prenatal Maturation of Oocytes 17
Postnatal Maturation of Oocytes 17
Comparison of Gametes 17
Uterus, Uterine Tubes* and Ovaries 18
Uterus 18
Uterine Tubes 18
Ovaries 18
Female Reproductive Cydes 20
Overton Cycle 20
Follicular Development 21
Ovulation 22
Corpus Luteum 22
Menstrual Cyde 23
Phases of Menstrual Cycle 24
Transportation of Gametes 25
Oocyte Transport 25
Sperm Transport 25
Maturation of Sperms 26
Viability of Gametes 26
Sequence of Fertilization 27
Phases of Fertilization 29
Fertilization 29
Cleavage of Zygote 30
Formation of Blastocyst 33
Summary of First Week 35
Clinically Oriented Problems 36
Second Week of Human Development 39
Completion of Implantation of Blastocyst 39
Formation of Amniotic Cavity, Embryonic Disc, and Umbilical Veside 41
Development of Chorionic Sac 42
Implantation Sites of Blastocysts 46
Summary of Implantation 46
Summary of Second Week 48
Clinically Oriented Problems 49
Third Week of Human Development SI Gastrulatlon: Formation of Germ Layers 51
Primitive Streak 52
Fata of Primitive Streak 54
Notochordal Process and Noto chord 54
Allantols 58
NeuruMom Formation of Neural Tube 58
Development off Somites 61 Development off Intreombryonic Coelom 62
Early Development of Cardiovascular System 62
Vasculogenesis and Angiogenesis 62
Primordial Cardiovascular System 62
Development off Chorionic Villi 63
Summary off Third Week 64
Clinically Oriented Problems 67
(5 Fourth to Eighth Weeks of Human Development 69
Phases of Embryonic Development 69
Folding off Embryo 70
Folding of Embryo in the Median Plane 70
Folding of Embryo in the Horizontal Plane 70
Germ Layer Derivatives 70
Control off Embryonic Development 72
Highlights off Fourth to Eighth Weeks 74
Fourth Week 74
Fifth Week 75
Sixth Week 78
Seventh Week 78
Eighth Week 84
Estimation of Embryonic Age 85
Summary of Fourth to Eighth Weeks 87
Clinically Oriented Problems 88
Fatal Periods Ninth Week to Birth 91
Estimation off Fetal Age 93
Trimesters of Pregnancy 93
Measurements and Characteristics of Fetuses 93
Highlights off Fetal Period 94
Nine to TweJve Weeks 94
Thirteen to Sixteen Weeks 95
Seventeen to Twenty Weeks 95
Twenty -one to Twenty-Five Weeks 96
Twenty -sex to Twenty-Nine Weeks 97
Thirty to Thirty-four Weeks 97
Thirty -five to Thirty-Eight Weeks 97
Expected Date of Dellvery 99
Factors Influencing Fetal Growth 99
Cigarette Smoking 99
Multiple Pregnancy 99
Alcohol and Illicit Drugs 99
Impaired Uteroplacental and Fetoplacental Blood Flow 99
Neural te and Neural Tuba 99
Neural Crest Formation 99
Genetic Factors and Growth Retardation 100
Procedures for Assessing Fetal Status 100
Ultrasonography 100
Diagnostic Amniocentesis 100
Alpha-Fetoprotein Assay 101
Spectrophotometry Studies 101
Chorionic Villus Sampling 101
Cell Cultures and Chromosomal Analysis 102
Noninvasive Prenatal Diagnosis 102
Fetal Transfusion 103
Fetoscopy 103
Percutaneous Umbilical Cord Blood Sampling 103
Magnetic Resonance Imaging 103
Fetal Monitoring 103
Summary off Fetal Period 103
Clinically Oriented Problems 104
ТУ Placenta and Fetal Membranes 107
Placenta 107
Decidua 109
Development of Placenta 109
Placental Circulation 111
Placental Membrane 113
Functions of Placenta 114
Placental Endocrine Synthesis and Secretion 117
The Placenta as an Allograft 117
The Placenta as an Invasive Tumor-like Structure 118
Uterine Growth during Pregnancy 118 Parturition 119
Stages of labor 119
Placenta and Fatal Membranes after Birth 121
Maternal Surface of Placenta 121
Fetal Surface of Placenta 121
UmbillqpJ Cord 124
Amnion and Amniotic Fluid 126
Umbilical Vasicla 129
Significance of Umbilical Vesicle 130
Fate of Umbilical Vesicle 130
Allantois 130
Multiple Pregnancies 130
Twins and Fetal Membranes 130
Dizygotic Twins 131
Monozygotic Twins 132
Other Types of Multiple Births 133
Summary of Placenta and Fetal Membranes 135
Neonatal Period 138
Clinically Oriented Problems 138
Body Cavities, Mesenteries, and Diaphragm 141
Embryonic Body Cavity 141
Mesenteries 144
Division of Embryonic Body Cavity 144
Development of Diaphragm 146
Septum Transversum 147
Pleuroperitoneal Membranes 147
Dorsal Mesentery of Esophagus 147
Muscular Ingrowth from Lateral Body Walls 148
Positional Changes and Innervation of Diaphragm 148
Summary of Development of Body Cavities, Mesenteries, and Diaphragm 151
Clinically Oriented Problems 153
Pharyngeal Apparatus, Face, and Neck 155
Pharyngee! Arches 155
Pharyngeal Arch Components 157
Pharyngeal Pouches 161
Derivatives of Pharyngeal Pouches 161
Pharyngeal Grooves 164
Pharyngeel Membranes 164
Development of Thyroid Gland 168
Histogenesis of Thyroid Gland 169
Development of Tongue 172
Lingual Papillae and Taste Buds 172
Nerve Supply of Tongue 173
Development of Salivary Glands 174
Development of Face 174
Development of Nasal Cavities 181
Paranasal Sinuses 181
Development of Palate 182
Primary Palate 182
Secondary Palate 182
Summary of Pharyngeal Apparatus, Face, and Neck 191
Clinically Oriented Problems 191
Respiratory System 195
Respiratory Primordium 195
Development of Larynx 196
Development of Trachea 198
Development of Bronchi and Lungs 200
Maturation of Lungs 201
Summary of Respiratory System 206
Clinically Oriented Problems 207
Alimentary System 209
Foregut 210
Development of Esophagus 210
Development of Stomach 211
Omental Bursa 211
Development of Duodenum 214
Development of Liver and Biliaiy Apparatus 217
Development of Pancreas 219
Development of Spleen 221
Midgut 221
Herniation of Midgut Loop 223
Rotation of Midgut Loop 224
Retraction of Intestinal Loops 224
Cecum and Appendix 225
Hindgut 233
Cloaca 233
Anal Canal 233
Summary of Alimentary System 234
Clinically Oriented Problems 239
Urogenital System 241
Development of Urinary System 243
Development of Kidneys and Ureters 243
Development of Urinary Bladder 255
Development el Urethra 258
Development of Suprarenal Glands 259
Development of Genital System 260
Development of Gonads 260
Development of Genital Ducts 262
Development of Male Genital Ducts and Glands 264
Development of Female Genital Ducts and Glands 264
Development of Vagina 266
Development of External Genitalia 267
Development of Male External Genitalia 267
Development of Female External Genitalia 268
Development of Inguinal Canals 276
Relocation of Testes and Ovaries 278
Testicular Descent 278
Ovarian Descent 278
Summary of Urogenital System 278
Clinically Oriented Problems 280
Cardiovascular System 283
Early Development of Heart and Blood Vessels 284
Development of Veins Associated with Embryonic Heart 285
Fate of Vitelline and Umbilical Arteries 288
Later Development of Heart 289
Circulation through Primordial Heart 291
Partitioning of Primordial Heart 293
Changes in Sinus Venosus 294
Conducting System of Heart 301
Birth Defects of Heart and Great Vessels 301
Derivatives of Pharyngeal Arch Arteries 317
Arch Arteries 317
Derivatives of Second Pair of Pharyngeal Arch Arteries 317
Derivatives of Third Pair of Pharyngeal Arch Arteries 318
Derivatives of Fourth Pair of Pharyngeal Arch Arteries 318
Fifth Pair of Pharyngeal Arch Pair of Pharyngeal 320
Derivatives of First Pair of Pharyngeal Fetal and Neonatal Circulation 325
Fetal Circulation 325
Transitional Neonatal Circulation 325
Derivatives of Fetal Vessels and Structures 329
Development of Lymphatic System 331
Development of Lymph Sacs and Lymphatic Ducts 331
Development of Thoracic Duct 331
Development of Lymph Nodes 331
Development of Lymphocytes 331
Development of Spleen and Tonsils 332
Summary of Cardiovascular System 332
Clinically Oriented Problems 334
Skeletal System 337
Development of Bone and Cartilage 337
Histogenesis of Cartilage 339
Histogenesis of Bone 339
Intramembranous Ossification 339
Endochondral Ossification 340
Development of Joints 341
Fibrous Joints 342
Cartilaginous Joints 342
Synovial Joints 342
Development of Vertebral Column 342
Development of Ribs 344
Development of Sternum 344
Development of Cranium 344
Cranium of Neonate 346
Postnatal Growth of Cranium 347
Development of Appendicular Skeleton 349
Summary of Skeletal System 363
Clinically Oriented Problems 353
Muscular System 355
Development of Skeletal Muscle 355
Myotomes 357
Pharyngeal Arch Muscles 358
Ocular Muscles 358
Tongue Muscles 358
Limb Muscles 358
Development of Smooth Muscle 358
Development of Cardiac Muscle 359
Summary of Muscular System 361
Clinically Oriented Problems 361
Development of Limbs 363
Early Stages of Limb Development 363
Final Stages of Limb Development 367
Cutaneous Innervation of Limbs 367
Blood Supply of Limbs 371
Birth Defects of Limbs 372
Summary of Limb Development 377
Clinically Oriented Problems 377
Nervous System 379
Development of Nervous System 379
Development of Spinal Cord 382
Development of Spinal Ganglia 384
Development of Spinal Meninges 385
Positional Changes of Spinal Cord 387
Myelination of Nerve Fibers 387
Development of Brain 392
Brain Flexures 392
Hindbrain 392
Choroid Plexuses and Cerebrospinal Fluid 396
Midbrain 396
Forebrain 396
Birth Defects of Brain 403
Development of Peripheral Nervous System 412
Spinal Nerves 412
Cranial Nerves 412
Development of Autonomic Nervous System 414
Sympathetic Nervous System 414
Parasympathetic Nervous System 414
Summary of Nervous System 414
Clinically Oriented Problems 415
Development of Eyes and Ears 417
Development of Eyes and Related Structures 417
Retina 419
Ciliary Body 423
Iris 423
Lens 425
Aqueous Chambers 426
Cornea 427
Choroid and Sclera 427
Eyelids 427
Lacrimal Glands 428
Development of Ears 428
Internal Ears 428
Middle Ears 430
External Ears 431
Summary of Eye Development 434
Summary of Ear Development 435
Clinically Oriented Problems 435
Integumentary System 437
Development of Skin and Appendages 437
Epidermis 437
Dermis 439
Glands 440
Hairs 445
Nails 446
Teeth 446
Summary of Integumentary System 454
Clinically Oriented Problems 454
Human Birth Defects 457
Classification of Birth Defects 457
Teratology: Study of Abnormal Development 458
Birth Defects Caused by Genetic Factors 458
Numeric Chromosomal Abnormalities 459
Structural Chromosomal Abnormalities 466
Birth Defects Caused by Mutant Genes 469
Developmental Signaling Pathways 471
Birth Defects Caused by Environmental Factors 472
Principles of Teratogenesis 472
Critical Periods of Human Development 472
Human Teratogens 475
Birth Defects Caused by Multifactorial Inheritance 484
Summery of Birth Defects 484
Clinically Oriented Problems 485
Common Signaling Pathways Used During Development 487
Intercellular Communication 488
Gap Junctions 488
Cell Adhesion Molecules 489
Morphogens 490
Retinoic Acid 490
Transforming Growth Factor-fJ and Bone Morphogenetic Proteins 490
Hedgehog 491
WNT/B-Catenin Pathway 492
Protein Kinases 493
Receptor Tyrosine Kinases 493
Hippo Signaling Pathway 494
Notch-Delta Pathway 494
Transcription Factors 496
HOX Proteins 496
PAX Qenes 496
Basic Helix-Loop-Helix Transcription Factors 497
Epigenetics 497
Histones 498
Histone Methylation 498
DNA Methylation 498
MicroRNAs 499
Stem Cells: Differentiation versus Pluripotency 499
Summary of Common Signaling Pathways Used During Development 500
Appendix 503
Index 513