MATHEMATICAL MORPHOLOGIC ANALYSIS OF AGING-RELATED EPIDERMAL CHANGES

Fractographic techniques based on mathematical morphology were used to study aging-related epidermal changes in abdominal skin samples obtai ned from 96 autopsy cases. Three linear roughness indices were evaluat ed for the rete peg profile and the shrinkage effect on the basal laye r and interface between the granular and horny layers. Elderly subject s had a 36.3% decrease in rete peg-related roughness index when compar ed with younger subjects. This roughness index has been corrected, wit h shrinkage due to skin elasticity taken into account. For females, fi tting of a logistic decay function yielded a curve with right and left asymptotes and a steeper descent between 40 and 60 years. Half value time-i.e., the time when half rete peg profile flattening occurred-was 46.8 years. In contrast, males showed almost monotonical decay. Epide rmal thickness measured between rete pegs showed the same exponential decline for both sexes, with values from 22.6 to 11.4 mum. Skin shrink age in elderly subjects decreased 22% in superficial layers and only 6 % in the lower epidermis. In both cases shrinkage had a linear relatio n with age, and no sex differences were found.