GONADS AND THE PITUITARY BODY 



bers occur in the female rat. They attributed this to the se- 

 cretion of a luteinizing hormone by the pituitary of the nor- 

 mal female. In their crucial experiment they first united 

 normal males and females (9 d^); they later hypophysecto- 

 mized the female. After the hypophysectomy, only an occa- 

 sional vaginal smear characteristic of oestrus was found in the 

 female (this never occurred if hypophysectomy was per- 

 formed in both animals of the pair, 9 cT). Five to fifteen 

 weeks after the hypophysectomy of the female, the male was 

 castrated — the pairs now being 9h ^.•^^ Oestrus, instead of 

 being delayed several weeks as in the pair 9 ^sT, appeared 

 within 4-5 days. The stimulation of follicular growth in the 

 female of the pair 9h ^, was even greater than in the pair 

 9 ^sf. From these as well as other experiments, Witschi and 

 Levine drew the following conclusions: (i) the pituitary of 

 the castrated male rat chiefly secretes a follicle-stimulating 

 hormone, and (2) the follicle-stimulating hormone inhibits 

 the secretion of the luteinizing hormone.-^' Only some weeks 

 after the parabiotic union, 9 ^, is the secretion of luteinizing 

 hormone by the pituitary of the normal female finally sup- 

 pressed. Witschi and Levine, however, do not attempt to ex- 

 plain why (in their experiments, at least) anoestrus and ab- 

 normally large numbers of corpora lutea were frequently ob- 

 served in the normal female in the first few weeks after the 

 establishment of parabiosis between a normal female and a 

 castrated male. 



The gonad-siimulating effects of the anterior pituitary after 

 gonadectomy. — In chapter i it was pointed out that gonadec- 

 tomy may be followed by anatomical changes in the pars 

 glandularis; this is strikingly illustrated in the rat. Engle 



^' 9h indicates a hypophysectomized normal female, ^h, a hypophysectomized 

 spayed rat, and so on. 



^^ Martins and Rocha (1930) transplanted the ovary to the kidney of castrated 

 and spayed rats. In the ovarian transplants in castrated males, only follicular 

 growth was observed, whereas in the transplants in spayed females there occurred 

 both follicular growth and the formation of corpora lutea. 



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