Organ Culture Studies of Reproductive Tracts 7 



results were similar with a replaced testis and one left attached 

 indicating that surgical removal of the testis did not cause 

 Wolffian duct retrogression. 



In contrast, in tracts with no testes the Wolffian ducts 

 underwent slow retrogression which involved successively, 

 reduction in diameter, loss of the lumen and then of the epi- 

 thelial component so that the ducts were discontinuous, and 

 finally loss of the surrounding sheath of mesenchymal origin. 

 Retrogression was mainly antero-posterior and by 3 to 4 days 

 of culture the ducts were practically gone anteriorly, except 

 for a small segment connected with the efferent ducts; the 

 posterior segment persisted and joined the prostatic urethra. 

 Testosterone in the clots (1 or 2 drops of 4(i.g./drop or 20(j.g./ 

 drop) prevented retrogression of the ducts after removal of 

 the testes. 



The results of culturing explants at the three older ages, 

 with both testes on the tracts or without testes, were essenti- 

 ally similar to the results with 15 + day-old explants. With 

 both testes present the Wolffian ducts persisted and developed 

 a slight epididymal coiling; without testes the ducts retro- 

 gressed. An important difference however, was observed in 

 tracts with only one testis (left in position or replaced). 

 Although both Wolffian ducts usually persisted, there was a 

 unilateral effect of the one testis if the tracts were spread in an 

 open Y-shape on the clots. It was apparent that the diameter, 

 and in some cases the continuity, of the gonadless Wolffian 

 duct depended upon its distance from the testis. Fig. 1 

 presents the results diagrammatically for explants cultured at 

 17+ days. 



In the gonadless tracts cultured at all four ages, testosterone 

 prevented retrogression of the Wolffian ducts. When ovaries 

 were substituted for testes the ducts retrogressed as in gonad- 

 less explants, and the same result was obtained in tracts 

 cultured at 15+ days with oestradiol. At older explantation 

 ages, oestradiol (1 or 2 drops of 0- 006 (xg. /drop in the clots) 

 caused a partial retention and some cystic enlargement of the 

 ducts in 5 out of 15 explants. 



