12 Dorothy Price and Richard Pannabecker 



oestradiol or oestradiol dipropionate (Greene, Burrill and Ivy, 

 1939, 1940). In the males, the results were variable and the 

 Wolffian ducts were normal in some foetuses but had retro- 

 gressed in others; the seminal vesicles were smaller and pro- 

 static buds were inhibited. These results suggest the possibility 

 of an inhibiting effect of oestrogen on testis hormone pro- 

 duction via the pathway of foetal hypophyseal gonadotropin 

 and, possibly, a direct stimulating action of oestrogen on the 

 male tract. However, hypophysectomy by decapitation in 

 the foetal rat has not shown that the hypophysis produces 

 gonadotrophin, which^is necessary for the secretion of testis 

 hormone (Wells, 1947* 1950). Jost (1953, 1954) has reviewed 

 the problem recently for several species. 



Summary and Conclusions 



The results of culture of foetal male reproductive tracts 

 indicate that testis hormone 1) maintains the Wolffian ducts, 

 2) stimulates the development of the primordia of the seminal 

 vesicles and their further growth and morphogenesis and 3) 

 causes an increase in the number of prostatic buds. The 

 testis hormone diffused through the explanted tracts and 

 produced local effects. 



It is suggested that these observations may apply to normal 

 sex differentiation in the rat and that foetal testis hormone 

 may be effective by local diffusion as well as by circulatory 

 pathways. 



Acknowledgement. 



This investigation was aided in part by Research Grant No. G. 2912 

 from the National Institutes of Health, Public Health Service, and by 

 the Dr. Wallace C. and Clara A. Abbott Memorial Fund of the Univer- 

 sity of Chicago. 



REFERENCES 



Fell, H. B. (1940). J. R. micr. Soc, 60, 95. 

 Greene, R. R. (1942). Biol. Symp., 9, 105. 



Greene, R. R., Burrill, M. W., and Ivy, A. C. (1939). Anat. Rec. y 74, 

 429. 



