116 



BIOLOGIC BASIS OF SEX 



MALE 



CASTRATE TYPE 



FEMALE 



Fig. 2.25. Diagrams summarizing the effects of castration on the development of the 

 syrinx (top row) oviducts, and genital tubercle (below) in bird embryos (chick and duck). 

 The left column shows the normal condition in the male : note the complete retrogression of 

 the Mlillerian ducts (broken lines) under the influence of the embryonic testes (black). In 

 the right column, the normal female condition showing the retrogression of the right oviduct. 

 The arrows indicate the inhibitory action normally exerted by the ovaries on the syrinx, 

 right oviduct and genital tubercle. The castrate type, which appears regardless of genetic 

 sex, is seen in the center. In castrates both oviducts persist in complete form and are as well 

 developed as the normal left oviduct ; the syrinx and genital tubercle, however, assume the 

 male form in the absence of the inhibition exerted by the ovaries. Note the extreme asym- 

 metry of the male syrinx and tubercle, as compared with the primitive symmetrical form 

 retained in the normal female. (After Et. Wolff and Em. Wolff, J. Exper. ZooL, 116, 59-97, 

 1951.) 



TABLE 2.2 



Effects of castration in male rabbit fetuses studied at the age of 2S days 

 (After A. Jost, Recent Progr. Hormone Res., 8, 379-418, 1953.) 



AGE AT CASTRATION 



MULLERIAN DUCTS 



WOLFFIAN DUCTS 

 AND DERIVATIVES 



PROSTATIC GLANDS EXTERNAL GENITALIA 



19 DAYS (2 coses) 



PERSISTENT 



20-21 DAYS (llcoses) 



PERSISTENT CAUDAL REMNANTS 



(in 3cases) 



VENTRAL BUDS 

 PRESENT 



22-23 DAYS (Scases) 



UTERO-VAGINAL 

 SEGMENTS PERSISTENT 



CAUDAL REMNANTS 



HYPOSPADIC 



23 DAYS (4 cases) 



ABSENT- SMALL 

 ABSENT (=NORMAL) SEMINAL VESICLES 

 PRESENT 



WELL DEVELOPED 



24 DAYS (3 coses) 



ABSENT ( = NORMAL) 



WELL DEVELOPED 



Unilateral castration is followed by normal development. 



Castration effects are prevented by Testosterone propionate 

 given at operation. 



yond a certain stage (about the 22nd day rather limited period during which involu- 



of gestation in the rabbit; Jost, 1947b, c) tion of the oviducts is determined, as was 



the ducts subsequently undergo involution shown also for the chick in the case of male 



as usual (Table 2.2). Evidently there is a hormones administered experimentally. 



