[Reproductive ability of germfree ICR female mice (author's transl)]

Reproductive ability of germfree and conventional female ICR mice was examined. Litter size and number of fetuses of germfree ICR mice kept in Facility A were smaller than those of Jcl: ICR mice. No difference was seen in oestrous cycle, pregnant rate, gestation period, weaning rate and number of corpora lutea between germfree and conventional mice. The small litter size of germfree mice seemed to be associated with early embryonic death before implantation. On the other hand, litter size of ex-germfree mice did not increase after conventionalization in Facility B.