A genetic characterization of differences in the sensitivity to radiation-induced malformation frequencies in the mouse strains Heiligenberger, C57BI, and Heiligenberger x C57BI.

We studied the frequency of malformations induced in two mouse strains (Heiligenberger, C57B1/6J) by exposure to x-rays 3 h after conception. Whereas there was a high number of malformed fetuses in Heiligenberger mice (mostly gastroschises) on day 19 of pregnancy, C57B1 did not respond to radiation exposure shortly after conception with an increased frequency of malformed fetuses. Cross-breeding of both strains revealed that no statistically significant increase in radiation-induced malformations was obtained in the F1 fetuses when the father was Heiligenberger and the mother C57B1. In the opposite case (Heiligenberger mother, C57B1 father) a small but statistically significant increase was observed.