Comparison of reactions to skin grafts in green frogs: Rana lessonae cam., R. esculenta L. and R. ridibunda pall.

Adult, field-collected green frogs, Rana lessonae and R. ridibunda, and their interspecific hybrid R. esculenta were tested with skin grafts at 22 +/- 2 degrees C. Two types of reactions to grafts were observed. 1) Median survival time (MST) was about 25 days, which was observed in R. lessonae hosts in response to allogeneic stimuli and to skin grafts from R. esculenta, and R. esculenta hybrids given grafts from the parental species. 2) MST was equal to or longer than 30 days, which was observed in the case of grafts among R. esculenta, and in R. ridibunda hosts given grafts from R. esculenta and R. lessonae. It seems that a high histocompatibility allele polymorphism occurs in R. lessonae even within one population, whereas lower polymorphism and/or reduced immunological reactivity occurs in R. ridibunda.