THE LATER DEVELOPMENT OF THE FROG 



163 



the ventral ends of the anterior gill pouches additional epithelial 

 proliferations are formed about the time the internal gills 



th 



ub 



V 



D 



FIG. 55. 



FIG. 56. 



FIG. 55. Diagram of the branchial pouch derivatives in the frog. After 

 Maurer, with Greil's modification, eg, Carotid gland; e\, ei, es, epithelioid bodies; 

 th, thyroid body; tmi, tm?, thymus bodies; ub, ultimobraiichial body; I VI, first 

 to sixth visceral pouches. (/, hyomandibular; II-VI, first to fifth branchial 

 pouches.) 



FIG. 56. Diagrams of the derivatives of the visceral pouches and arches in 

 the frog. After Maurer, with Greil's modification. A. Lateral view, frog larva. 

 B. Lateral view, after metamorphosis. C. Transverse section through gill of frog 

 larva. D. Transverse section through gill region, just after metamorphosis; 

 the gills have not quite disappeared, a, Afferent branchial arteries; c, carotid 

 gland; d, dorsal gill remainder; e, epithelioid bodies; g, internal gills; m, middle 

 gill remainder; o, operculum; s, sup^apericardial or postbranchial body; t, thyroid 

 body; th, thymus bodies; v, ventral gill remainder; I-VI, visceral arches; 

 /, mandibular arch; II, hyoid arch; III VI, first to fourth branchial arches; 

 1-6, visceral pouches; 1, hyomandibular pouch; 2, hyobranchial pouch; 3-6, 

 first to fourth branchial pouches. 



appear. Those derived from the first branchial pouch form the 

 carotid glands, while the others form the so-called epithelioid 



