GONADOTROPIC SUBSTANCES 



the detection of prolan (Schneider, 1930; Friedman and 

 Lapham, Wilson and Corner, 1931). Although it has been 

 said that approximately i "rat-unit" of prolan per kilo- 

 gram rabbit is the ovulation dose when administered intra- 

 venously, there is no evidence that the effects produced in 

 these different animals are due to the same substance. Hill, 

 Parkes, and White (1934) studied the factors which might 

 influence ovulation in groups of rabbits receiving different 

 doses of prolan. The "curve of response" found by them is 

 reproduced in Figure 41; its shape differs from that found in 

 similar experiments with anterior pituitary extract (Fig. ^S)- 

 They observed that the response of animals diminished after 

 three tests (at intervals of 3 weeks) had been made. 



The diagnosis of pregnancy. — The detection of prolan in 

 the urine or blood of pregnant women is unquestionably the 

 best means of diagnosing early pregnancy. In experienced 

 hands the test probably indicates pregnancy in 98 or 99 per 

 cent of cases. The numerous reports since the first given by 

 Aschheim and Zondek do not require consideration. 



THE PREPARATION OF PROLAN; THE PROPERTIES OF PROLAN 



The preparation of prolan. — By the earlier methods,-'' prolan 

 was prepared from raw or concentrated urine, which often 

 was first acidified, by the addition of various concentrations 

 of alcohol or acetone or of ammonium sulphate to saturation. 

 Most of the prolan was carried down with the precipitate. 

 Separation of the prolan from some of the inert substances 

 could be effected by repeated alcoholic precipitation, by the 

 addition of colloidal iron or tannic acid, or by dialysis. 

 Subsequent work has also shown that crude prolan often be- 

 haves like a protein, or as if it can be adsorbed on proteins 



^'Zondek and Aschheim, Biedl (1928); Dickens, Zondek (1930); Wiesner and 

 Marshall (1931); and Evans, Meyer, and Simpson (1933). "Emmenin" which 

 Collip prepared from the placenta is no longer considered to be a gonad-stimulating 

 substance but rather a compound of oestriol (see Collip and others, 1930, 1931, 1933, 

 1934, and Butenandt and Browne, 1933)- 



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