GONADOTROPIC SUBSTANCES 



ent preparations of prolan assayed by accepted techniques in 

 different laboratories, it will be difficult to decide what is the 

 quantitative relationship of prolan effects in the rat as com- 

 pared with the mouse. Zondek (1929), Hamburger (1933), 

 White and Leonard (1933), Reiprich (1934), Rowe, Simond, 

 and Nelson (1934), and Nelson and Overholser (1935) be- 

 lieved that the rat was the more sensitive (i mouse-unit 

 equivalent to 2 or more — usually about 4 — rat-units). How- 

 ever, Katzman and Doisy (1932) estimated that an imma- 

 ture rat required about four times as much hormone as an 

 immature mouse. Inasmuch as Katzman and Doisy based 

 their assays on indirect effects (opening of vaginal orifice and 

 oestrus), their results cannot be compared with those of 

 others. On the other hand, the same preparations were as- 

 sayed only in rats by Katzman and Doisy and by Rowe and 

 his co-workers, and were found to have about the same po- 

 tency. Other results of Rowe, Simond, and Nelson indicated 

 that assays by the technique of Katzman and Doisy cannot 

 be done accurately in mice. Less has been written about 

 qualitative or other quantitative differences, Bourg (1930) 

 believed that follicular hemorrhage occurred less frequently 

 in rats; Brouha and Simmonet (1930) concluded that follicu- 

 lar maturation and corpus luteum formation were more pro- 

 nounced in rats. Some of the effects of prolan on the ovaries 

 and uteri of immature rats are illustrated in Figures 34 and 



35- 



If prolan be administered for several days to immature rats 

 about 3 weeks old, and a well-marked development of corpora 

 lutea appears, the ovarian changes are not markedly in- 

 creased by increasing the dose ten- to fifty-fold (Evans, Mey- 

 er, and Simpson, 1931; Fluhmann, 1932; and Collip, Selye, 

 Anderson, and Thomson, 1933). However, morphological 

 changes in the ovaries and uterus can probably be detected 

 earlier (e.g., ^4-30 hours) after the administration of large 

 doses (Reiprich, 1934). Moreover, moderate doses of prolan 



[187] 



