6 Frances Carter, Marion C. Woods and Miriam E. Simpson 



assayed carefully in hypophysectomized immature rats. The end point, or 

 RU, in the assay was the minimal dose which would cause resumption of 

 follicular growth (Table 4). 



Table 4. Assay for Pituitary Follicle-stimulating Hormone (FSH) 

 IN Hypophysectomized Female Rats (after Simpson, 21) 



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



Inject SQ, 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 growth of follicles from 

 control size (< 375 n) to beginning antrum formation (450-500 n). 



The purified FSH preparations were made from sheep pituitaries by 40% 

 ethanol extraction of whole glands followed by fractional ammonium sulfate 

 precipitation, anion-exchange chromatography on DEAE-cellulose and 

 further ammonium sulfate fractionation. 



The best preparations had minimal effective doses (RU) for FSH ranging 

 from 4.0 down to 1.7 /xg, when given subcutaneously over a 3-day-period, 

 and did not show contamination with ICSH by interstitial cell repair until 

 25 to 70 times this dose was injected by the intraperitoneal route (IP), 

 likewise for 3 days. As can be seen (Table 5), the process of purification 



Table 5. Purification of Sheep FSH (after Simpson, 21) 



reduced the MED for FSH from 2.5 mg in the original glands to 1.7 ^g in 

 the final product. Whereas the original glands gave interstitial repair at 0.4 

 the MED for FSH the final product could be given at 70-fold the MED 

 before evidence of presence of ICSH was obtained. 



The favorable comparison with potency of other purified sheep FSH 

 preparations is shown in Table 6 (3-5, 11, 15, 17, 25, 30, 31). To be noted 

 particularly is the relative potency for FSH, and the contamination with ICSH 

 present in the NIH-FSH-Sl standard. By the assay method used here this 

 preparation had an MED of >50 jug and showed contamination with ICSH 

 at 5-fold this dose. It may be noted that Velardo in the recent report on 

 induction of ovulation in hypophysectomized rats (28) used this standard, a 



