DEVELOPMENT OF DEFINITIVE BODY FORM 



883 



CHROMAFFIN TISSUE 

 FORMING MEDULLA 

 OF ADRENAL GLAND 



Fig. 367. Differentiation of the adrenal (suprarenal) body. (A) Early stage in prolif- 

 eration of adrenal cortical primordium from coelomic epithelium. (B) Later stage of 

 cortex, forming rounded masses associated with cephalic ends of mesonephros. The 

 anterior end of the mesonephros lies between the adrenal body and lateral wall of the 

 coelom. (Compare fig. 3H and B.) (C) Cells from sympathetic ganglia penetrating 

 medial side of primitive cortical tissue of adrenal body to form chromaffin cells of 

 adrenal medulla. 



life, then comes to form the "inner cortical zone" or androgenic zone 

 (Howard, '39). 



8. Gonads 



The developing gonads were described in Chapter 18, and their hormonal 

 functions were outlined in Chapters 1 and 2. 



C. Possible Influence of Endocrine Secretions on the Development of 

 Definitive Body Form 



1. Thyroid and Pituitary Glands and Anuran Metamorphosis 



One of the earlier studies in this field of development was that by Guder- 

 natsch ('12 and '14) which showed that mammalian thyroid gland fed to 

 anuran, and urodele larvae stimulated growth, differentiation, and metamor- 

 phosis. In a later series of studies by Allen (see Allen, '25, for references 

 and review) and by Hoskins ('18 and '19), it was demonstrated that the 

 removal of the thyroid gland in young tadpoles of Rana and Bujo prevents 

 metamorphosis from the larval form into that of definitive body form (i.e., 



