Is upward basal cell movement independent of mitosis in the normal epidermis?

Abstract

An analysis has been made of the possible mechanisms by which cells leave the basal layer distally during cell replacement in the steady state mammalian epidermis. Etoh's concept (1975) of cells actively migrating from the basal layer is challenged. Computer experiments suggest that if basal cell migration is an active process, the rate of cell migration consistent with the kinetics of the process being examined would yield a depopulation value far higher than the one observed experimentally. We found by contrast that rates of migration comparable to those found experimentally after mitosis inhibition by irradiation were obtained in our computer simulation experiments if it was assumed that distal basal cell migration is a passive event resulting from cells being extruded from the basal layer. We believe that there is not at present sufficient data to support the concept of active cell migration from the basal layer. The evidence favours the concept that in normal steady state epidermal populations, cells are passively removed from the basal layer as a result of forces generated, directly or indirectly, by dividing cells.

Migration and Mitosis in the Epidermis

“…In a recent article, Mitrani (1983) asked the question 'Is upward basal cell movement independent of mitosis in the normal epidermis? ', that is, whether migration is an active or passive process.…”

“…That many cells disappear from the basal layer is a quantitated observation and that this precedes any mitotic or DNA synthetic burst is the only point that was being made. Mitrani (1983). ( x } Active migration model of Mitrani (1983).…”

“…Mitrani (1983). ( x } Active migration model of Mitrani (1983). Theoretical simulations do little to resolve the question of the chicken and egg conundrum (which comes first, migration or mitosis?)…”

Migration and mitosis in the epidermis

“…The computer simulations reported by Mitrani (1983) ask, and in my opinion answer, a very specific question: Is it true that the experimental data presented by Etoh et al (1975) cannot be explained on the basis of the passive migration hypothesis? I claim that the answer to this question is no.…”

“…My work was concerned with specifically analysing the data presented in Figs I, 2 and 6 by Etoh, Taguchi & Tabachnick (1975) and, as Potten and his colleagues correctly state, Etoh et al in their paper present data almost entirely from guinea-pig epidermis. The confusion between mouse and guinea-pig epidermis might have generated a certain amount of misunderstanding, but it seems to me that their Comment article indicates a more basic misunderstanding of the significance of my theoretical analysis (Mitrani, 1983).…”