Vaginal septa in mice: incidence, inheritance, and effect on reproductive, performance.

Dorso-ventral vaginal septa were observed in 38% of the recently weaned BALB/cJ female mice in the production colony at The Jackson Laboratory. The frequency of septa in two other BALB/c substrains and eight different inbred strains ranged from 0 to 8%. The vaginal anomaly was similar regardless of genetic background although individual variations were observed. The remainder of the reproductive tract was normal. Microscopically, the septum consisted of a fibrous partition covered by normal epithelium. Genetic analysis was undertaken by outcrossing septate BALB/cJ females to C57BL/6J, DBA/2J, or BALB/cBy males. Examination of female F1 and F2 progeny indicated more than one recessive gene was involved and genetic background influenced expression of these genes. Reproductive performance of septate and nonseptate BALB/cJ females was compared using several criteria. Fewer septate females were fertile, but the fecundity of fertile septate females was not affected.