490 THE EEPEODUCTIVE SYSTEM 



However, the experiments of Steinach (Zentralblatt f. Physiol., 27, 14, 

 1913) cannot be ignored in tliis connection. Steinach made reciprocal 

 transplantations of testes and ovaries in young male and female rats and 

 in guinea pigs, and claims to have succeeded in changing a potential 

 female, from the view point of secondary sex characters (both physical and 

 temperamental), into a male, and vice versa. A male is said to have devel- 

 oped functional mammary glands, and even to have suckled young. Stein- 

 ach interprets his results to mean that not only do the secondary sex char- 

 acters of the male and female depend upon the presence of the 'pubertal 

 gland' (interstitial cells), but also the fact whether the undifferentiated 

 gonad shall develop into a testis or an ovary. Microscopic examination of 

 the transplant showed that everything suffered degeneration except Ihe in- 

 terstitial tissue, which underwent extensive hyperplasia. For further in- 

 formation on this and related subjects reference should be made to Mar- 

 shall's "The Physiology of [Reproduction," 1910. 



The Duct System 



Tubuli Recti. At the apex of the testicular lobule the tortuous 

 seminiferous tubules pass into the rete testis of the mediastinum. At 

 this point the tubule becomes straight and is abruptly narrowed. Thus 

 the short straight tubules, tubuli recti, are formed. In the straight 

 tubules the stratified epithelium of the tortuous portions is abruptly' 

 exchanged for a very low columnar or flattened type of epithelium with 

 which the Sertoli cells of the tortuous tubules seem to be continuous. 

 The straight tubules are very short and are soon transformed into the 

 irregular anastomosing canals of the rete testis. 



Rete Testis. The connective tissue of the mediastinum is perme- 

 ated by a network of irregular channels of varying diameter which 

 present frequent dilatations and often have the appearance of broad 

 cleft-like spaces. These are the canals of the rete testis which form a 

 dense network of anastomosing channels. On the one hand they receive 

 the straight tubules, and on the other they pass into the ductuli ef- 

 ferentes, which convey the secretion onward to the globus major of the 

 epididymis. 



The canals of the rete testis are lined by cuboidal or flattened epi- 

 thelium, which rests upon a delicate basement membrane. This in 

 turn is supported by the connective tissue of the mediastinum. The 

 broad but irregular lumen of the canals is occupied by the secretion 

 from the seminiferous tubules and contains many spermatozoa. 



Ductuli Efferentes, As the tubules of the rete testis leave the 



