180 



Discussions 



depression of LH activity and a relatively marked depression of FSH potency was 

 present. There is no comparable data on sheep and very little information on other 

 species in the literature. Bogdanove, Spirilos and Halmi {Htulociinolo^y 51, 302, 1955) 

 found that total gonadotropin content was low in the pituitaries of rats with hypo- 

 thalamic lesions and testicular atrophy. Davidson, Contopoulos and Ganong 



Table 1. Pituitary Gonadotropin Content of Sheep 

 Values are means + standard error of the mean. Assayed against Armour FSH and LH. 



EFFECT OF HYPOTHALAMIC LESIONS ON 

 PITUITARY GONADOTROPHIN CONTENT IN MALE DOGS 



I 



16r 



TESTES PRESENT 



CASTRATE 



14 - 



12 



10 



FSH ICSH 

 CONTROL 



FSH ICSH 

 LESION OF 

 POSTERIOR 

 TUBER CINEREUM 



FSH ICSH 

 CONTROL 



FSH ICSH 



LESION OF 



POSTERIOR 



TUBER CINEREUM 



Fig. 4. 



{Endocrinology, in press, I960) found depression of both FSH and LH activity in 

 dogs with posterior median eminence lesions and testicular atrophy. In the rat and the 

 dog, lesions which led to testicular atrophy were generally more posterior than those 

 in the ewes with acyclic ovaries, but the significance of this point is difTicult to assess. 

 There was some discussion this morning about the locus of the feedback of gonadal 

 hormones in regulating gonadotropin secretion. I noticed that most of the speakers 

 were noncommittal, indicating the site of feedback in their diagrams by arrows 

 pointing both to the pituitary and hypothalamus. It is interesting in this regard that 

 while castration causes a sharp rise in the pituitary content of both FSH and LH 



