Cytokinetics of epidermic cells in skin from human cadavers. II. Dependency on sex, age, and site

Kinetic data on the labeling index (LI), DNA synthesis time (ts), and potential doubling time (tpot) of epidermic cells in relation to sex, age, and site were obtained by in vitro incubation of skin cylinders from 45 human cadavers with DNA precursors 3H- and 14C-thymidine. In a first study on parts of the same material, it was established that LI over a period of more than 70 h and tpot over a period of at least 30 h remained essentially unchanged and are comparable with live humans, when the cadavers were stored at 4 degrees C. The following results were obtained: The female and male cadavers had a LI of 2.6% (+/- 0.8%) or 2.5% (+/- 0.8%), a ts of 3.9 h (+/- 0.2 h) or 5.0 h (+/- 1.6 h), and a tpot of 168.5 h (+/- 34.3 h) or 183.9 h (+/- 27.2 h). The LI for the thigh and knee ranged between 21.3% and 25.8% in different age groups. No statistically relevant differences were established between the sexes or among the age groups. Topographic allocation of the proliferative-kinetic data ultimately showed that, on the average, LI was relatively high at the elbow (3.1% +/- 1.0%) with short tpot (109.3 +/- 72.5 h) and a comparatively large epidermal diameter (47.1 microns); by contrast, LI at the lower abdomen was impressively low (2.1% +/- 0.8%), tpot relatively long (183.0 +/- 138.7 h) and mean epidermal diameter relatively small (23.0 microns). Nevertheless, no statistically relevant differences were established between data for elbow and lower abdomen or between other data for different sites. The proliferative-kinetic data for human cadavers were compared with data reported in the literature for live humans.