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NEURULATION AND EARLY ORGANOGENY 



Sense plate 



Optic plate 

 Optic vesicle 



Stomodeal invagination 



Oral sucker 

 A face view of the 5 mm. frog tadpole. 



to degenerate. The ventral limit of the vertical groove becomes the 

 ectodermal stomodeum when it breaks through to the endodermal 

 pharynx to form the mouth. That part of the mouth derived from the 

 stomodeum will therefore be lined with ectoderm. The dorsal limit 

 of the vertical groove becomes the hypophyseal invagination. Di- 

 rectly dorsal to each oral sucker, above and to either side of the 

 stomodeal cleft, there develop large oval evaginations (bulbous out- 



Optic 

 protuberance 



G'" onloge 



Pronephric 

 region 



Hypophysea 

 invagination 



Stomodeal cleft 



Anlagen of the head region: 5 mm. frog tadpole. 



