Potential risk of light and room temperature exposure to preimplantation embryos.

Adverse effects of simultaneous exposure to visible light and room temperature were investigated in rabbit early cleavage stages and morulae. Routine laboratory conditions were mimicked as close as possible. Embryonic development was assessed by cell proliferation via incorporation of tritiated thymidine, by gross morphology, and by electron microscopy. Damage was detectable in both stages at 1-hour exposure by statistically significant impaired cell proliferation. Compared with single exposure to each individual stressor, combined exposure to light and room temperature amplified detrimental effects. Ultrastructural analysis of light-exposed cleavage stages revealed no indication of cell injury at 4-hour exposure. Gross morphology proved to be too inaccurate to evaluate damage imposed by exposure toward both physical factors investigated.