HORMONES IN DIFFERENTIATION OF SEX 



113 



A B 



Fig. 2.23. The effects of sex hormones on development of the sex ducts in chick embryos. 

 A. Normal female embryo of 18 days, showing development of the left oviduct with shell 

 gland, and retrogression of the right. B. Genetic male embryo, 18 days, treated with 2.0 mg. 

 estrone. Both oviducts are present and greatly hypertrophied. Compare with C for the nor- 

 mal condition. C. Normal male embryo at 17 days of incubation. Note the paired Wolffian 

 ducts and absence of both oviducts. D. Genetic female embryo at 17 days, after treatment 

 with 1.0 mg. androsterone, showing absence of both oviducts and extreme hypertrophy of the 

 Wolffian ducts. For the normal female anatomy compare with A, and for normal size of 

 male ducts see C. (From B. H. Willier, in Sex and Internal Secretions, 2nd ed., The Williams 

 & Wilkins Co., 1939.) 



duct, uterine tube, and vaginal canal 

 (Greene, 1942; Burns, 1939b, 1942a and b; 

 Moore, 1941; Raynaud, 1942; Jost, 1947a). 

 Details of structure depend on the state of 

 development of the rudimentary Miillerian 

 ducts in the males of the species in question. 

 The vagina may be defective or absent en- 

 tirely in males of certain species, as in the 

 opossum, in which the duct is usually incom- 

 plete, without a connection to the urino- 

 genital sinus. In other species the effects are 

 slight or lacking entirely (Raynaud, 1950, 

 the field mouse; White, 1949, the hamster; 

 Davis and Potter, 1948, man). 



The effects of male hormones. The effects 

 of male hormones on the ]\liillerian ducts 

 are more variable; strong inhibitory effects 

 are obtained in many species and under 

 proper experimental conditions; but with 

 large doses stimulating or "paradoxical ef- 

 fects" often appear, such as have been de- 

 scribed in the case of the gonads. The 

 time of administration of the hormone is 

 important. Both in chick embryos and in 

 larval amphibians treatment with androgens 

 before the appearance of the duct, or during 



the formative period, may result in total 

 suppression.^^ In amphibians, in which the 

 ]\Iiillerian duct develops slowly, a particu- 

 larly interesting situation is found. Early 

 administration of testosterone propionate 

 prevents development entirely (Burns, 

 1939c; Foote, 1941, Amhystoma) or may 

 leave only the ostial rudiment (Gallien, 

 1955, Pleurodeles) ; however, treatment dur- 

 ing the period of formation may result in 

 suppression of the unformed portion of the 

 duct, while the part already laid down per- 

 sists and with large doses may even be 

 strongly hypertrophied (Mintz, 1947). Here 

 is a striking paradox in which different re- 

 gions of the same structure (which are, how- 

 ever, developmentally of different age) 



" See, for example, for amphibians, Burns, 1939c ; 

 Foote, 1941; Hanaoka, 1941b: for the chick, Wil- 

 lier, 1939; Wolff, 1938, 1950; Gaarenstroom, 1939; 

 Stoll, 1948; Huijbers, 1951. Exceptions must be 

 noted, however, in a few cases: the field mouse 

 (Raynaud, 1950); the hamster (Bruner and Wits- 

 chi,'l946, White, 1949); man (Davis and Potter, 

 1948) in which no clear effects were observed, 

 whether because of true species differences or other 

 experimental variables is not clear. 



