X CONTENTS 



Gastrulation as a Critical Stage in Development 101 



Pre-gastrulation Stages 103 



Definition of the Major Processes of Gastrulation 107 



Gastrulation Proper 109 



Chapter Eight. Neurulation and Early Organogeny 123 



Neurulation 123 



Early Organogeny 124 



Surface Changes 124 



Visceral Arches 131 



Origin of the Proctodeum and Tail 132 



Internal Changes 136 



Chapter Nine. A Survey of the Major Developmental Changes 



IN the Early Embryo 139 



Chapter Ten, A Survey of the Later Embryo or Larva 155 



Chapter Eleven. The Germ Layer Derivatives 161 



The Ectoderm and Its Derivatives 161 



The Brain 161 



The Spinal Cord 167 



The Peripheral Nervous System 169 



The Organs of Special Sense 170 



The Cranial Nerves 181 



The Spinal Nerves 185 



The Neural Crest Derivatives 188 



The Stomodeum and Proctodeum 189 



Chapter Twelve. The Endodermal Derivatives 193 



The Mouth (Stomodeum, Jaws, Lips, Etc.) 193 



The Foregut 194 



The Midgut 205 



The Hindgut 206 



Chapter Thirteen. The Mesodermal Derivatives 209 



The Epimere (Segmental or Vertebral Plate) 209 



The Mesomere (Intermediate Cell Mass) 218 



The Hypomere (Lateral Plate Mesoderm) 231 



Appendix: Chronological Summary of Organ Anlagen Appear- 

 ance OF Rana pipiens 251 



Glossary of Embryological Terms 261 



Bibliography for Frog Embryology 311 



Index 321 



