Objective To determine the effects of lensspecific overexpression of OSM on the eye development. Methods A truncated mouse OSM c DNA (661 bp) was linked to the αA-crystallin promoter. Transgenic mice were characterized by routine histological and immunohistochemical techiniques. TUNEL assays were used to de tect cell death. The mRNA expression of caspase-3 was detected by in situhybridization, Rabbit anti-cleavage caspase-3 antibody was used to detectactive capase-3. Results At embryonic day (E) 14.5 and 17.5, expression of the OSM transgenic protein was detected specifically in lens fiber cells. The onset of retinal degeneration in the mid portion of the transgenic retinae was observed started from E17.5. By the time of birth 50% or more of the retinal cells were missing. The OSM transgenic retinal cells underwent apoptosis indicated by TUNEL assays. Most strikingly, activation of caspase-3 protein were observed throughout the transgenic retinas. Conclusions Lens-specific overexpression of OSM activate caspase-3, leading to abnormal eye development,apoptosis and widespread retinal degeneration. (Chin J Ocul Fundus Dis，2003，19：201-268)