An Overview of Developmental Events, Processes, and Abnormalities . 1

The First and Second Weeks. 2

The Embryonic Period

The Early Embryonic Period. 3

The Late Embryonic Period. 4

The Fetal Period. 5

Histological Concepts

Samples of Epithelia and Connective Tissue . 6

Skin and Embryonic Connective Tissue. 7

Induction. 8

Apoptosis . 9

Segmentation and Early Pattern Formation

Genetic Determination of Embryonic Axes and Segments. 10

Segmentation and Segment Fates. 11

Cell Adhesion and Cell Migration. 12

Cell Differentiation and Cell Fates . 13

Growth Factors. 14

Classification of Abnormal Processes . 15

Classification of Multiple Anomalies. 16

Normal Versus Major Versus Minor Malformations . 17

Marfan Syndrome. 18

Apert and De Lange Syndromes. 19

Examples of Deformations . 20

Example of a Deformation Sequence . 21

Drug-Induced Embryopathies. 22

Terminology. 23

Chapter 2

Early Embryonic Development and the Placenta . 27

Adult Uterus, Ovaries, and Uterine Tubes . 28

Ovary, Ova, and Follicle Development . 29

The Menstrual Cycle and Pregnancy. 30

The First Week: .

Ovulation, Fertilization and Migration Down the Uterine Tube. 31

Ectopic Pregnancy. 32

Tubal Pregnancy. 33

Interstitial, Abdominal, and Ovarian Pregnancy. 34

The Second Week: .

Implantation and Extraembryonic Membrane Formation. 35

The Third Week: Gastrulation. 36

Events Related to Gastrulation:.

Neurulation and Early Placenta and Coelom Development . 37

The Fourth Week: Folding of the Gastrula . 38

The Vertebrate Body Plan. 39

Formation of the Placenta. 40

The Endometrium and Fetal Membranes. 41

Placental Structure . 42

External Placental Structure; Placental Membrane. 43

Placental Variations . 44

Placenta Previa. 45

Summary of Ectodermal Derivatives. 46

Summary of Endodermal Derivatives . 47

Summary of Mesodermal Derivatives. 48

Terminology. 49

Chapter 3

The Nervous System. 51

Formation of the Neural Plate. 52

Neurulation. 53

Neural Tube and Neural Crest . 54

Neural Tube Defects

Defects of the Spinal Cord and Vertebral Column. 55

Defects of the Brain and Skull. 56

Neuron Development. 57

Development of the Cellular Sheath of Axons . 58

Development of the Spinal Cord Layers. 59

Development of the Spinal Cord. 60

Peripheral Nervous System

Development of the Peripheral Nervous System. 61

Somatic Versus Splanchnic Nerves . 62

Growth of the Spinal Cord and Vertebral Column. 63

Embryonic Dermatomes. 64

Adult Dermatomes . 65

Development of the Brain

Early Brain Development. 66

Further Development of Forebrain, Midbrain, and Hindbrain. 67

Development of Major Brain Structures. 68

Growth of the Cerebral Hemispheres. 69

Derivatives of the Forebrain, Midbrain, and Hindbrain . 70

Development of the Forebrain

Forebrain Wall and Ventricles. 71

Relationship Between Telencephalon and Diencephalon . 72

Cross Sections of the Midbrain and Hindbrain. 73

Production of Cerebrospinal Fluid . 74

Development of Motor Nuclei in the Brainstem. 75

Segmentation of the Hindbrain. 76

Development of the Pituitary Gland. 77

Development of the Ventricles. 78

Congenital Ventricular Defects. 79

Terminology. 80

Chapter 4

The Cardiovascular System. 83

Early Vascular Systems. 84

Vein Development

Early Development of the Cardinal Systems . 85

Transformation to the Postnatal Pattern. 86

Vein Anomalies. 87

Aortic Arch Arteries . 88

Artery Anomalies

Aortic Arch Anomalies. 89

Anomalous Origins of the Pulmonary Arteries. 90

Intersegmental Arteries and Coarctation of the Aorta. 91

Summary of Embryonic Blood Vessel Derivatives. 92

Formation of Blood Vessels. 93

Formation of the Heart Tube

Formation of the Left and Right Heart Tubes. 94

Formation of a Single Heart Tube. 95

Chambers of the Heart Tube. 96

Bending of the Heart Tube. 97

Partitioning of the Heart Tube. 98

Atrial Separation. 99

Spiral (Aorticopulmonary) Septum . 100

Completion of the Spiral (Aorticopulmonary) Septum. 101

Ventricular Separation and Bulbus Cordis. 102

Adult Derivatives of the Heart Tube Chambers. 103

Fetal Circulation. 104

Transition to Postnatal Circulation . 105

Congenital Heart Defect Concepts. 106

Ventricular Septal Defects. 107

Atrial Septal Defects. 108

Spiral Septum Defects. 109

Patent Ductus Arteriosus. 110

Terminology. 111

Chapter 5

The Respiratory System. 113

Early Primordia. 114

Formation of the Pleural Cavities . 115

The Relationship Between Lungs and Pleural Cavities . 116

Visceral and Parietal Pleura . 117

Development of the Diaphragm. 118

Congenital Diaphragmatic Hernia. 119

Airway Branching

The Airway at 4 to 7 Weeks. 120

The Airway at 7 to 10 Weeks. 121

Development of Bronchioles and Alveoli . 122

Bronchial Epithelium Maturation . 123

Congenital Anomalies of the Lower Airway. 124

Airway Branching Anomalies. 125

Bronchopulmonary Sequestration. 126

Palate Formation in the Upper Airway. 127

The Newborn Upper Airway. 128

Terminology. 129

Chapter 6

The Gastrointestinal System and Abdominal Wall . 131

Early Primordia. 132

Formation of the Gut Tube and Mesenteries. 133

Foregut, Midgut, and Hindgut. 134

Abdominal Veins . 135

Foregut and Midgut Rotations. 136

Meckel’s Diverticulum . 137

Lesser Peritoneal Sac. 138

Introduction to the Retroperitoneal Concept. 139

Midgut Loop. 140

Abdominal Ligaments. 141

Abdominal Foregut Organ Development . 142

Development of Pancreatic Acini and Islets. 143

Congenital Pancreatic Anomalies. 144

Development of the Hindgut . 145

Congenital Anomalies

Duplication, Atresia, and Situs Inversus. 146

Megacolon (Hirschsprung’s Disease). 147

Summary of Gut Organization . 148

Development of the Abdominal Wall. 149

Umbilical Hernia . 150

The Inguinal Region. 151

Anterior Testis Descent. 152

The Adult Inguinal Region . 153

Anomalies of the Processus Vaginalis. 154

Terminology. 155

Chapter 7

The Urogenital System. 157

Early Primordia. 158

Division of the Cloaca . 159

Congenital Cloacal Anomalies . 160

Pronephros, Mesonephros, and Metanephros. 161

Development of the Metanephros. 162

Ascent and Rotation of the Metanephric Kidneys. 163

Kidney Rotation and Migration Anomalies

Kidney Rotation Anomalies and Renal Fusion. 164

Kidney Migration Anomalies and Blood Vessel Formation . 165

Hypoplasia. 166

Ureteric Bud Duplication. 167

Ectopic Ureters. 168

Bladder Anomalies. 169

Allantois/Urachus Anomalies . 170

Primordia of the Genital System. 171

8-Week Undifferentiated (Indifferent) Stage . 172

Anterior View of the Derivatives. 173

Paramesonephric Duct Anomalies . 174

Homologues of the External Genital Organs. 175

Hypospadias and Epispadias. 176

Gonadal Differentiation . 177

Testis, Epididymis, and Ductus Deferens . 178

Descent of Testis. 179

Ova and Follicles. 180

Summary of Urogenital Primordia and Derivatives. 181

Summary of Genital Primordia and Derivatives . 182

Terminology. 183

Chapter 8

The Musculoskeletal System. 185

Myotomes, Dermatomes, and Sclerotomes. 186

Muscle and Vertebral Column Segmentation . 187

Mesenchymal Primordia at 5 and 6 Weeks . 188

Ossi?cation of the Vertebral Column. 189

Development of the Atlas, Axis, Ribs, and Sternum. 190

Bone Cells and Bone Deposition . 191

Histology of Bone. 192

Membrane Bone and Skull Development. 193

Bone Development in Mesenchyme. 194

Osteon Formation. 195

Compact Bone Development and Remodeling. 196

Endochondral Ossi?cation in a Long Bone. 197

Epiphyseal Growth Plate

Epiphyseal Growth Plate. 198

Peripheral Cartilage Function in the Epiphysis. 199

Structure and Function of the Growth Plate. 200

Pathophysiology of the Growth Plate. 201

Ossification in the Newborn Skeleton. 202

Joint Development . 203

Muscular System: Primordia. 204

Segmentation and Division of Myotomes. 205

Epimere, Hypomere, and Muscle Groups. 206

Development and Organization of Limb Buds. 207

Rotation of the Limbs. 208

Limb Rotation and Dermatomes. 209

Embryonic Plan of the Brachial Plexus. 210

Divisions of the Lumbosacral Plexus. 211

Developing Skeletal Muscles . 212

Terminology. 213

Chapter 9

Head and Neck. 215

Ectoderm, Endoderm, and Mesoderm. 216

Pharyngeal (Branchial) Arches . 217

Ventral and Midsagittal Views . 218

Fate of the Pharyngeal Pouches . 219

Midsagittal View of the Pharynx. 220

Fate of the Pharyngeal Grooves . 221

Pharyngeal Groove and Pouch Anomalies. 222

Pharyngeal Arch Nerves. 223

Sensory Innervation Territories. 224

Development of Pharyngeal Arch Muscles

Early Development of Pharyngeal Arch Muscles. 225

Later Development of Pharyngeal Arch Muscles. 226

Pharyngeal Arch Cartilages. 227

Ossi?cation of the Skull . 228

Premature Suture Closure. 230

Cervical Ossi?cation. 231

Torticollis . 232

Cervical Plexus. 233

Orbit. 234

Ear Development . 235

Adult Ear Organization. 236

Summary of Ear Development . 237

Cranial Nerve Primordia. 238

Cranial Nerve Neuron Components. 239

Parasympathetic Innervation and Unique Nerves. 240

Development of the Face

Development of the Face: 3 to 4 Weeks. 241

Development of the Face: 4 to 6 Weeks. 242

Development of the Face: 6 to 10 Weeks. 243

Palate Formation

Palate Formation. 244

Interior View of Palate Formation; Roof of Oral Cavity. 245

Congenital Anomalies of the Oral Cavity. 246

Floor of the Oral Cavity . 247

Developmental Coronal Sections . 248

Tooth Structure and Development . 249

Dental Eruption. 250

Terminology. 251