Some Aspects of the Characterization of Pregnant Mare Serum Gonadotrophin

Since the first demonstration of the presence of a gonadotrophin in the serum of pregnant mares (Cole & Hart, 1930), many attempts have been made to isolate this hormone (PMSG) in pure form (Li, 1949, for a summary of earlier literature; Bourillon & Got, 1957). It is known that the hormone concentrate possesses both follicle-stimulating (FSH) and interstitial cell-stimulating (ICSH) activity (Cole et al., 1950); no clear-cut separation of the two types of activity has as yet been obtained. Although it has been reported recently that the crude gonadotrophin can be resolved into three biologically active components by means of paper electrophoresis (Frahm & Schneider, 1957), from the data presented it is not possible to conclude whether or not the components actually represent three distinct activities, or if the results cannot be explained on the basis of dosages alone. The work reported here represents an attempt to further purify active