GONADS AND THE PITUITARY BODY 



in the normal female rat in Experiments 6(9?) and 7 ( 9 sf ) 

 (Levine and Witschi, 1933). 



If testicular tissue is administered to the castrated male 

 rat of the experiment 9 sT, the changes in the ovaries of the 

 normal female rat are less pronounced (Martins and Rocha, 



1930)- 



In Experiments 6(99) and 7 ( 9 ^), the changes in the 

 genital tract of the normal female were compared by Hill 

 (1933). In Experiment 7 ( 9 sT) the more or less continuous 

 oestrus and the formation of cystic follicles in the ovary ap- 

 peared earlier (e.g., if corpora lutea were present in the ovary 

 at the time the rats were united) and were more pronounced. 

 These observations suggested that the pars glandularis of the 

 castrated rat secretes more gonadotropic hormone than that 

 of the spayed rat. 



In the experiments 9 9 and 9 cf , impregnation of a fe- 

 male may be accomplished. Pregnancy in one female in the 

 experiment 9 9 seems to prevent oestrus in the other normal 

 rat (Hill, 1932; however, Zacherl, 1928, found no disturbance 

 of the oestrous cycles). Some growth of the mammary gland 

 may occur in the normal rat. If the female rat of the experi- 

 ment 9 cf becomes pregnant, the course of pregnancy is nor- 

 mal; the mammary glands, however, develop poorly, and the 

 mother does not nurse the young. 



Precocious sexual maturity can be produced in immature 

 female rats as in the experiment 9 9 , in which both animals 

 are immature. No changes in the secondary sexual organs of 

 the spayed female are observed (Kallas, 1929). In other ex- 

 periments in young (but perhaps not sexually immature) 

 male rats, Kallas found that at first the testes and seminal 

 vesicles of the normal rat were enlarged in the experiments 

 cTsT and cT 9 . 



The interpretation of the results of the parabiosis experiments. 

 ■ — If a gonadectomized and a normal rat are united surgically 

 so that an interchange of their blood and lymph occurs, there 



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