Light microscopic radioautographic study on DNA synthesis in aging mice corneas.

The morphological change and DNA synthesis of the aging mice corneal cells were investigated by light microscopic radioautography after injection of tritiated thymidine. The result showed that the incorporation of tritiated thymidine in corneal cells changed with aging. The sites of tritiated thymidine incorporation were located in the epithelium from postnatal day 19 to 1 year after birth, in the stroma and endothelium from prenatal day 19 to postnatal day 8 only. The labeling index in the epithelial cells reached its highest value at 1 month after birth. Labelled stromal and endothelial cells reached their peaks simultaneously on the third day after birth and disappeared completely from postnatal 1 month onwards. The thickness of the cornea increased obviously at one month and there were no notable morphological change thereafter. Our investigation provides for the first time a systematic study on the age-related changes of DNA synthesis and construction in the aging mice corneas.