THE GONADOTROPIC HORMONES 



Methods of securing purified hormone have been described 

 lately by Evans and others (1936), Gustus, Meyer, and 

 Woods (1936), and Cartland and Nelson (1937). Gustus, 

 Meyer, and Woods adsorbed the hormone on a suspension of 

 A1(0H)3 from which elution was accomplished by means of 

 dilute NH4OH. Cartland and Nelson not only described in 

 detail a method of making very potent extracts but also 

 studied some of the hormone's properties. It was found to be 

 soluble in serum containing 50 per cent acetone or 60 per cent 

 ethanol. When the percentage of acetone or alcohol was 

 raised to 70 per cent (pH 6) the greater part of the gonado- 

 tropic substance was precipitated. Further manipulation 

 permitted the isolation of preparations of a potency of 0.05 

 mg. for each rat-unit. (In terms of ovarian effect, their rat- 

 unit was 2-10 times as potent as that used by others.) The 

 hormone could be inactivated by HCHO (4 per cent, pH 8.0, 

 3 hours) or heat at 70° C. or above. Inactivation by heat was 

 studied at three hydrogen-ion concentrations: pH 6.0, 7.0, 

 and 8.0. Destruction, especially at 70° C, was greatest at pH 

 6.0 and least at pH 8.0. Enzymic destruction took place in 

 the presence of trypsin (also reported by others), but not in 

 the presence of emulsin or invertin. The high concentration 

 of hydrogen ions necessary for investigating the effect of pep- 

 sin produced inactivation in the absence of the enzyme. 



The investigation of Evans and his colleagues is of inter- 

 est because of their finding that suitable concentrations of 

 (NHJ2SO4 can be used to fractionate pregnant-mare serum 

 into two components, one chiefly stimulating follicle-growth 

 and the other causing a "hypertrophy of the theca interna 

 and interstitial tissue" without follicle growth or the forma- 

 tion of lutein tissue. The second fraction restored the func- 

 tion of the interstitial cells of hypophysectomized rats. The 

 follicle-stimulating fraction apparently was not free from the 

 second principle; its action in male rats after hypophysec- 

 tomy was not described. Hellbaum (1937) declared that fol- 

 licle-stimulating, luteinizing, and augmenting substances can 



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