THE USE OF THE MALE NORTH AMERICAN FROG (RANA PIPIENS) IN THE DIAGNOSIS OF PREGNANCY¹

Abstract

While it has been known for some time that the African clawed frog (Xenopus laevis) could be stimulated to mating by the injection of mammalian gonadotropins (Shapiro, 1936), this reactivity has only recently been utilized for the demonstration and titration of such hormones (Robbins, Parker and Bianco, 1947). It was found that the male frog reacted far more quickly than the female and furthermore was 64 times as sensitive to pituitary gonadotropin and 10 times as sensitive to chorionic gonadotropin. These facts naturally led to an investigation of the possibility of the use of the male Xenopus laevis for the diagnosis of pregnancy. However, the animal proved unsatisfactory for such tests. The difficulties encountered and possible explanation of them will be discussed in another paper. Ample evidence existed from previous work suggesting the possible use of other species of male frogs or toads. In 1929 Houssay,