128 



BIOLOGIC BASIS OF SEX 



stituents of the organ respond to the appro- 

 priate hormone in a highly specific manner. 

 The erectile bodies, the development of 

 which largely determines the form and the 

 size of the penis, are strongly stimulated by 

 male hormone and almost entirely inhibited 

 by female hormone (Fig. 2.33j. Qualita- 

 tively, these responses are independent of 

 sex constitution, but with identical dosages 

 marked differences in size, such as were 



noted previously in the case of the prostate, 

 the sinus epithelium and derivatives of the 

 sex ducts (Figs. 2.29 and 2.24) , are again ob- 

 served in the two sexes. Female hormone, in 

 addition to inhibiting the erectile tissue, in- 

 duces an extreme hyperplasia of the vulvar 

 and periurethral connective tissues (Fig. 

 2.335). It is this response which produces 

 the gross swelling of the vulvar region, so 

 conspicuous in estrogen treated embryos of 



.,*m^''- 



Fig. 2.33. The effects of male and female hormone^ on the differentiation of the histologic 

 constituents of the phallus in young opossums. A. The effects of androgen in a male, aged 30 

 days, treated from birth onward. There is great hypertrophy of the erectile bodies but 

 otherwise structiue is normal; at the top, the paired corpora cavernosa are imited at the 

 mid-line ; below, the urethral canal, with the bulbo-urethral glands on either side ; laterally, 

 the large bulbs of the corpora spongiosa, with their muscular investments. B. The effects of 

 estrogen in another male littermate. The erectile bodies are almost completely suppressed 

 and there is an enoimous hyperplasia of the periurethral connective tissue. The urethral 

 canal (urinogenital sinus) is greatly enlarged, as in a female, and the sinus epithelium is 

 transformed into stratified scjuamous epithelium like that of the fully developed vaginal 

 canals. The sex of the subject makes no difference in the character of these responses. 



