CONGENITAL EYE DEFECTS IN MOUSE .2. INFLUENCE OF LITTER SIZE, LITTER SPACING, AND SUCKLING OF OFFSPRING ON RISK OF EYE DEFECTS IN C57BL MICE

Eye defects including corneal capacity, microphthalmia, cataract, and anophthalmia occur spontaneously in C57BL mice. Breeding experiments with substrain C57BL/10ChPr described in the present report indicated that the probability of inclusion of animals with eye defects in litters subsequent to the first is influenced by litter spacing, litter size, and suckling of offspring. Second and third litters were as likely to include progeny with eye defects as were first litters if they resulted from matings taking place after weaning of the previous litter or if the mother was prevented from suckling her previous litter. If the gestation period overlapped with suckling of young from a previous litter the resulting litter contained fewer offspring and animals with eye defects were less likely to be included. Reduction in litter size appeared to result from embryonic losses prior to the time of implantation. The prevalence of overlap between gestation and suckling of young, in matings used for stock maintenance, led to an apparent decline with increasing litter rank in the frequency of litters that included progeny with eye defects. Copyright © 1969 Wiley‐Liss, Inc., A Wiley Company