The Role of the Pituitary Gonadotropins 9 



given in Table 9. Judged by the assay procedure described the best prepara- 

 tions had an MED of 1 /^g and did not lead to resumption of follicular 

 development at 6000-fold this dose. No other pituitary tropic hormones 

 were present in significant amounts in these ICSH preparations. 



Table 8. Assay for Pituitary Interstitial Cell-stimulating Hormone (ICSH) in 

 Hypophysectomized Female Rats (after Simpson, 21) 



Strain, Long-Evans. H 26-28 days, 7 days PO. 



Inject IP 1 X day, 3 days Autopsy 72 hr. 



RU: Minimal total dose, in a graded series of doses, giving microscopic 

 evidence in two-thirds of the animals of repair of "deficient" 

 interstitial cells : increased nuclear size, loss of pyknosis ; reappear- 

 ance of rim of eosinophilic cytoplasm. 



Table 9. PuRincATioN of Sheep ICSH (after Simpson, 21) 



* IP. t S.Q. 



The purity of these preparations can be judged by comparing them with 

 those from sheep pituitaries made elsewhere, shown in Table 10 (13, 14, 23, 

 24, 30). 



The comparison of potency of ICSH with different standard preparations 

 (NIH and Armour) by two different assay methods is given in Table 1 1 . The 

 best preparation was 4 times as potent as the Armour "LH" standard, 

 judged by the repair of interstitial tissue of hypophysectomized female rats, 

 and 5 times as potent by the ventral prostate test in hypophysectomized male 

 rats (21). 



Table 12 shows a preliminary effort to determine whether the efficacy of 

 more purified FSH preparations is increased by reinstating the ICSH content 

 to 10%. The two FSH preparations used, with MED's of 5 and 1.67 /xg 

 respectively, did not cause ovulation during the preparatory stimulation of 

 follicular growth when given in doses of 4 RU combined with 10% ICSH. 

 When this preparatory treatment was supplemented as before by FSH alone, 

 given at twice the total dose used in the preparatory treatment (or 8 RU FSH), 

 ovulation occurred in most rats and large numbers of ova were shed. A 

 supplement of the combination (FSH + 10% ICSH) gave comparable 



