Proliferative activity of the sebaceous glands of the aged.

In order to study the effects of ageing on the sebaceous follicles in man, gland size was determined by planimetry and cellular kinetics studied by autoradiography. Twenty-one excisional biopsies from the cheeks of 16 aged subjects (M = 69 ± 5 yr) were compared to younger age groups, namely 5 from adults (M = 50 ± 3 yr), and 15 from young adults (M = 28 ± 8 yr). [ 3 HJ-thymidine or [ 3 H]-histidine were injected 45', 7, 13, 19 and 25 days prior to excision. Autoradiographs were evaluated with standard criteria. The size of the sebaceous glands increase with age. Expressed in mm 2 the mean size rose from .2258 ± 0.5 to .4003 ± 21 (p ≤ .01). Likewise the mean percentage share of sebaceous tissue within the total specimen rose from 37.6 ± 17 to 45.7 ± 24. The mean largest sebaceous glands within the 3 age groups rose from .3614 ± 15 to .5060 ± 23 (p ≤ .05). The turnover of the sebaceous glands in the aged is slowed down compared to young adults. Labeled sebocytes migrate slowly out of the acini and are retained longer with a peak of total labeled cells between 7 and 13 days. Therefore sebum production declines with high age despite a diffuse sebaceous gland hyperplasia.