Impact of the environment on the XXXX corneal epithelium.

@entity1 @entity620 @entity95 @entity7462 @entity735 @entity4378 @entity291 @entity9050
PURPOSE: To evaluate whether the content of @entity620 in the corneal epithelium and @entity7462 reflects seasonal fluctuations in parallel with environmental changes. METHODS: @entity4378 , @entity291 , @entity95 , and @entity1 were examined, to cover a broad spectrum of overlapping habitats. @entity620 was determined by high-performance liquid chromatography. The thickness of the corneal epithelium was measured, and the number of cells was counted in the tissue sections. RESULTS: Three groups of @entity4378 eyes were used, two of them collected during summer, the third group during winter. @entity9050 content did not show seasonal variation in either the corneal epithelium or the @entity7462 , whereas epithelial thickness and number of cells decreased significantly from summer to winter. In @entity291 , @entity9050 content, thickness of the epithelium, and number of cells were lower in animals tended indoors compared with those tended outdoors, whereas @entity9050 level in the @entity7462 remained similar in both cases. The @entity95 showed significantly reduced @entity9050 content in the corneal epithelium but not in the @entity7462 in @entity735 . This procedure did not change epithelial thickness, but the number of cells was slightly increased. The mean epithelial thickness in @entity1 corneas successively decreased with increasing latitude and decreasing radiation exposure from the summer season in Oslo to the midnight sun, polar night, conditions in Troms  , 10 degrees far north, although the differences did not reach statistical significance. CONCLUSIONS: Ambient radiation is needed to sustain high @entity620 concentration in the corneal epithelium. Corneal epithelial thickness and number of cells are prone to seasonal fluctuations regulated by ambient radiation. In contrast, @entity9050 content of the @entity7462 is uninfluenced by environmental change. It is suggested that seasonal adaptation of @entity1 corneal epithelium in response to variation in ambient radiation may be nature's strategy for countering radiation damage to the eye.
