GESTATION 



987 



test requires only 4 hours and a larger num- 

 ber of animals can be utilized, thus decreas- 

 ing the error due to use of inadequate num- 

 bers of animals. Comparison of the rat 

 hyperemia and the Friedman tests revealed 

 that the former is slightly more accurate 

 but a little less sensitive (Albert, 1949). 



Within two years after the publication of 

 the Friedman test for pregnancy, Shapiro 

 and Zwarenstein (1934a, 1934b, 1935) and 

 Bellerby (1934) reported the use of the 

 African toad {Xenopus laevis, D) in the 

 diagnosis of pregnancy. Again the test was 

 based on the ability of HCG to induce the 

 extrusion of ova by the frog following the 

 injection of the urine into the dorsal lymph 

 sac. Extrusion of the ova occurred in 6 to 

 15 hours and the test was shown to compare 

 favorably with both the Aschheim-Zondek 

 and Friedman tests, although it did not give 

 tiie graded response seen with the A-Z test 

 (Crew, 1939). Weisman and Coates (1944) 

 found an accuracy of 98.9 per cent with the 

 Xenopus test over a 5-year period during 

 which 1000 clinical cases were examined. 



Galli-Mainini (1947) first reported the 

 use of the male batrachian in the diagnosis 

 of pregnancy and Robbins, Parker and 

 Bianco (1947) simultaneously reported the 

 release of sperm by Xenopus following 

 treatments with gonadotrophins. Galli-Mai- 

 nini (1948» pointed out that this reaction 

 is not restricted to a single toad, but would 

 ]irobably be found in many frogs and toads. 

 He added that care should be used to em- 

 ploy animals with a continuous spermato- 

 genesis. This was immediately confirmed by 

 reports from different countries using vari- 

 ous species of frogs and toads endogenous 

 to the areas. Immediate use of Rana pipiens 

 was reported in the United States and this 

 species became very popular in that country 

 ( Wiltberger and :\Iiller, 1948) . 



The advantages of the sperm-release test 

 are the time requirements, simplicity, end 

 point, and opportunity to use many animals. 

 On the other hand, the reaction is all or 

 none and shows no gradation in degree of 

 reaction. In general, the urine is injected 

 into the dorsal lymph sac and the cloaca 

 aspirated for sperm 1 to 3 hours later. Al- 

 though this is the most recent of the preg- 

 nancy tests, many reports have appeared 



and some evaluation as to accuracy may be 

 attempted. Galli-IVIainini (1948) reported 

 an accuracy of 98 to 100 per cent in a sum- 

 mary of more than 3000 tests and 100 per 

 cent accuracy for negative results in more 

 than 2000 controls. Robbins (1951 ) reported 

 an accuracy of 89.5 per cent in the first tri- 

 mester of pregnancy. Pollak (1950) indi- 

 cated that as many as 20 per cent of the 

 negative tests obtained in the summer were 

 false. This suggested the existence of a 

 refractory state at this season. Bromberg, 

 Brzezinski, Rozin and Sulman (1951) re- 

 ported on a comparison of several tests 

 including 700 cases. An accuracy of 85 per 

 cent was obtained with the male frog test, 

 99 per cent with the rat hyperemia test, 98.5 

 per cent with the Friedman test and 98 per 

 cent with the Aschheim-Zondek test. The 

 authors indicate that the 15 per cent failures 

 to get a positive reaction in the frog could 

 be due in part to the poor sensitivity of the 

 animal which could only be overcome by 

 concentrating and detoxifying the urine. 

 Comparison of the minimal amounts of 

 HCG to elicit a positive reaction are Vs 

 I.U. for the rat hyperemia test, 1 I.U. for 

 the Aschheim-Zondek and Hyla tests, 2 

 I.U. for the Rana and Bufo tests, and 5 

 I.U. for the Friedman test. Reinhart, Caplan 

 and Shinowara (1951) reported an accuracy 

 of 99 per cent with 840 urine specimens; 

 only 3 false negatives were noted in 346 

 specimens from known pregnant women 

 and no false positives noted in 125 non- 

 pregnant women. The authors attribute the 

 high degree of accuracy to standardization 

 of the procedure by which extraneous fac- 

 tors were eliminated. These include ( 1 ) the 

 use of 2 or more 30- to 40-gm. frogs for 

 each test, (2) elimination of all animals suf- 

 fering from red leg and other diseases, (3) 

 adequate time for sperm release, (4) con- 

 centration of the urine, (5) maintenance 

 of frogs at 15 to 22°C., and (6) during the 

 summer the injection of an increased volume 

 of urine and an increase to 4 hours in the 

 period for sperm release. The maintenance 

 of frogs in a hibernating state by keeping 

 them in a refrigerator at 38°F. has been re- 

 i:)orted to insure a high degree of sensitivity 

 regardless of the season (Allison, 1954). 

 Although it is obvious that more data are 



