Epidermal proliferation characteristics are similar in the pilary canal of mouse hair follicles and in interfollicular epidermis.
Proliferation characteristics of basal cells in the pilary canal of resting hair follicles were investigated and compared with corresponding parameters in interfollicular epidermis of hairless mice. The mitotic rates had similar 24-h means at both locations. Distinct circadian rhythms which showed phasing and amplitudes similar to that in interfollicular epidermis, were demonstrated by the 3H-TdR labelling index, the mitotic rate and the mitotic index. Influx of cells to and efflux of cells from the S phase were measured in the early morning and in the evening by a 3H-TdR double labelling method. The influx values were similar at both times of both locations. The efflux values recorded in the morning were more than twice the values seen in the evening in both the pilary canal and in interfollicular epidermis. The epidermal motitic rate in the pilary canal was depressed by epidermal extracts, and increased after adhesive tape stripping in the same way as in interfollicular epidermis. The results indicate no heterogeneity in cell proliferation characteristics between the two locations, and suggest that similar mechanisms are responsible for maintainance of growth equilibrium at both sites.
D000818:Animals; D002455:Cell Division; D002940:Circadian Rhythm; D004247:DNA / Q000096:biosynthesis; D000078404:Epidermal Cells; D006197:Hair / Q000166:cytology*; D008297:Male; D051379:Mice; D008812:Mice, Hairless; D008938:Mitosis; D008940:Mitotic Index
D004247:DNA