The effect of wounding on epidermal cell proliferation in the tail skin of C57B1/6J mice was examined. The hoaeostatic labeling Index (LI) of basal epidermal (BE) cells of control (CO) animals was 7.62 ±0.43, and did not vary depending on the time of day. Using a tape-stripping model of wounding, injury to the tail skin at 0600, 0900, 1500, 1800, 2100, and 2400 hr with examination 24 hrs later increased the LI of BE cells by more than 2-fold from uninjured control values. However, the LI of BE cells injured at 1200 hr and examined 24 hrs later was 4-fold greater than CO levels, or 100t more than injury at any other time of day. Unwounded areas adjacent to the injured region had Lis comparable to CO values at all time points. Furthermore, mice wounded at 1200 hr and terminated 27 hrs later (i.e., 1500 hr) had Lis 52« greater than mice wounded at 0900 hr and examined 27 hrs later at 1200 hr the following day. These results indicate: a) the LI of BE cells is dependent on the time of wounding, b) the magnitude of the LI was dependent on the duration after wounding as well as the time of wounding, c) the LI of unwounded BE cells in animals undergoing re-epithellalizatlon was similar to noninjured BE levels regardless of the time of Injury, and d) there is no diurnal rhythm in DNA synthesis in homeostatic BE cells of tall skin. Supported In part by NIH grant NS20500.
|Original language||English (US)|
|State||Published - Dec 1 1996|
All Science Journal Classification (ASJC) codes
- Molecular Biology