Open eyelids at birth, a new mutation in the musk shrew, Suncus murinus.

The mutation designated "open eyelids at birth" arose spontaneously in the BAN strain of the musk shrew (Suncus murinus). This is the first report on this kind of mutation in the shrew. Mating experiments suggested that the mutant character is controlled by an autosomal recessive gene with about 43% penetrance. The symbol oeb(open eyelids at birth) was proposed for the mutant gene. Affected shrews were fully viable and fertile. Phenotypically, the affected shrews were characterized by one or both eyelids open at birth. By 9 days of age, the exposed and dried eyeballs usually dropped off and became missing or sometimes looked microphthalmic. Except for the eye abnormality, the affected shrews showed no obvious external abnormalities. Light-microscopically, the affected shrews with missing eyes or microphthalmia-like eyes did not have complete eye structures, and only remnants of some eye tissue were observed. In the phenotypically normal oeb/oeb shrews with closed eyelids at birth, no histological eye abnormalities were noted. Thus, the mutant character observed may simply be caused by a failure of the eyelids to close.