Sex-reversal in frogs and toads. A review of the recorded cases of abnormality of the reproductive system and an account of a breeding experiment

Protogynous Sex Change in the Reed Frog Hyperolius viridiflavus

“…Many authors have reported cases of abnormality in the reproductive system of amphibians found in the field (Crew, 1921;Witschi, 1930;Moore, 1944) and Witschi (1923) gave an account of simultaneous hermaphroditism in Rana temporaria where two frogs had well developed ovaries and testicular nodules with fertile eggs and spermatozoa; however, no behavioral or life history data indicating that this occurs in the field were provided. Crew (1921) actually found a R. temporaria with typical male secondary sexual characteristics in amplexus with a female and later showed by dissection that this individual had two ovotestes structured like normal testes with only a few degenerate ova included. All offspring from his breeding experiment were female, showing that this individual, although behaving and functioning as a male, was probably a genetic female.…”

Sex Reversal: A Fountain of Youth for Sex Chromosomes?

“…All turned out to be fertile, the XY female producing clutches with male‐biased sex ratios (1:3) including YY males, and the YY males siring all‐male progenies. Matsuba et al (2008) recently reported an event of mass feminization in a northern‐Finland population of Rana temporaria , a species in which spontaneous sex‐reversal had already been documented (Crew 1921; Witschi 1929). The sex ratio of breeding adults was strongly female‐biased in years 1999–2000, with a progressive return to an even sex ratio thereafter.…”

The Occurrence of Oviform Germ Cells by Hormonal Injection in the Regenerated Testes of a Newt

“…In the gonads of the amphibians in nature the oviform germ cells were reported mostly by chance and rather few in number, while in the gonads of operated amphibians large number of the oviform cells were often found in the series of experimental animals. Search of literature will be omitted in the present paper because nearly complete references to the occurrence of oviform cells in testes in nature have been given in the reports of Crew (1921), S,wingle (1922), Tso-Hsin Cheng (1921) and others. Following the review of the several different ideas put forth for the explanation of the occurrence, of these aberrant germ cells, a mere morphological observation of the oviform cells accidentally developed in the testis, cannot suffice to answer the problem of their significance and the only way to approach solution is open to experiments.…”