GONADS AND THE PITUITARY BODY 



and Aschheim). The lack of complete development of the 

 immature ovary and the atrophic changes in the senile ovary 

 are therefore not clearly due either to an absence of gonado- 

 tropic hormone in the anterior pituitary or to an inability of 

 the ovary to respond to the hormone. It may be that an in- 

 sufficient quantity of gonadotropic hormone is available, or 

 that the hormone is liberated at a slower rate than in young 

 adult animals. 



Adult female mice respond in much the same way as imma- 

 ture mice.^ In adult female rats, however, the predominant 

 effect is a stimulation of follicular growth with the formation 

 of numerous cysts, both small and large. The ova in such 

 cystic follicles undergo degeneration. After maximum follicu- 

 lar growth has occurred, lutein cells may be formed from the 

 theca interna and the granulosa; the corpora lutea finally 

 grow to a size greater than that found in the normal adult rat 

 (Engle and Smith, 1929). 



Smith (1927, 1930) has shown that the administration of 

 homo-implants to hypophysectomized rats restores the atro- 

 phic female gonads to normal. 



The effects in male animals. — Smith and Engle studied the 

 effects of implants of the anterior pituitary in immature and 

 mature male mice and rats. In immature male animals the 

 effects on the gonads were much less pronounced than in im- 

 mature female animals. Five or six implants, administered as 

 one implant each day to immature male rats, had no effect on 

 the size of the testis, but did cause an increase in the size of 

 the rest of the genital tract amounting to about 50 per cent. 

 After ten or more implants, similarly administered, there was 

 a definite increase in the size of the testis as well as a much 

 more pronounced effect on the size of the rest of the genital 

 tract. In the accessory organs there was histological evidence 



■* Engle (1927) mated adult female mice into which he had implanted mouse 

 pituitary tissue. When the mice were killed 9-10 days after mating he could find as 

 many as 19-29 nidation-sites in the uterine horns of a single mouse. 



[115] 



