FACTORS INFLUENCING ACTIVITIES OF THE TESTIS 



35 



the scrotum results in a corresponding failure of the seminiferous tubules 

 to produce sperm. In these instances the testis may appear shriveled and 

 shrunken (fig. 18). However, such cryptorchid (ectopic) conditions in most 

 cases retain the ability to produce the sex hormone at least to some degree. 

 A question therefore arises relative to the factors which inhibit seminiferous 

 tubule activity within the cryptorchid testis. 



The failure of cryptorchid testes to produce viable sperm has been of 

 interest for a long time. Observations have demonstrated that the more hidden 



Fig. 18. Experimental unilateral cryptorchidism in adult rat. The animal's left testis 

 was confined within the abdominal cavity for six months, whereas the right testis was 

 permitted to reside in the normal scrotal position. Observe the shrunken condition of the 

 cryptorchid member. (After Turner: General Endocrinology, Philadelphia, Saunders.) 



the testis (i.e., the nearer the peritoneal cavity) the less likely are mature 

 sperm to be formed. A testis, in the lower inguinal canal or upper scrotal 

 area is more normal in sperm production than one located in the upper 

 inguinal canal or inside the inguinal ring. Studies made upon peritoneal and 

 scrotal temperatures of rats, rabbits, guinea pigs, etc., demonstrate a tem- 

 perature in the scrotum several degrees lower than that which obtains in 

 the abdomen. These observations suggest that the higher temperature of the 

 non-scrotal areas is a definite factor in bringing about seminiferous tubule 

 injury and failure to produce sperm. 



With this temperature factor in mind. Dr. Carl R. Moore (in Allen, 

 Danforth, and Doisy, '39) and others performed experiments designed to 

 test its validity as a controlling influence. They found that confinement alone 

 of an adult guinea pig testicle in the abdomen led to marked disorganization 

 of all seminiferous tubules in seven days. After several months of such con- 



