HORMONES IN DIFFERENTIATION OF SEX 



81 



Fig. 2.3. Transplantation of the salamander gonad in early larval life (Burns, 1928): 

 previously unpublished photographs. A. A large, but somewhat degenerate, grafted ovary 

 lies just anterior to (above) the gonads of the host, which show changes in external form in 

 the vicinity of the graft. B. Cross-section of host's right testis at the level of the white line, 

 showing normal medullary development with well differentiated testis lobules, and periph- 

 erally a strongly developed cortex. 



A B 



Fig. 2.4. Diagrams illustrating Humphrey's orthotopic transplantation method. A. Posi- 

 tion of the gonad- and mesonephros-forming area of the embryo (stippled) which is excised 

 and reimplanted in the corresponding position in a host embryo from which the primordium 

 has just been removed. B. Cross-section of host at later stage showing position of the im- 

 planted material (between heavy lines) at the left. In the mesodermal layer a part of the 

 lateral mesoderm lies below, the gonad- and mesonephros-forming material above, with 

 the Wolffian duct at the top. Medial to the Wolffian duct lies the mass of primordial germ 

 cells (more densely stippled). 



