SKIN RELIEF AND AGING 187 lOO 8o 60 ÷ 40. DEPTH prn ß ßß ß ß ß ß ß ß ß ß : . _oo- 0_00 ß 210 ß ß ß ß ß ß ß ß ß o ß ß ß ß ß ß ß ß ß ß ß ß ß AGE 20 I I 0 60 80 1•)0 Figure 8. Individual depth of furrows (/am) in relation to age. c) the secondary axis disappears d) there is an increase in the C.D.S.S. The separate examination of results in individuals showed that these modifications did not reach the same level for all subjects. They appeared at different ages and sometimes late in life. Our technique did not permit differences in relation to sex to be observed. Examination of microphotographs of skin surface replicas shows a number of furrow directions for all subjects, even in the aged group. In this work, with the image analysis technique, we found, with very few exceptions (7 subjects), only one principal direction in the aged group. The difference of furrow orientations between children and adults (Figure 3 and Figure 4) is not important: there is a joining of the principal and secondary directions keeping the forearm axis in between. The angle between the two furrow axes diminishes, and the segments become pointed. This difference, observed between adult and aged groups, might be explained by the looseness of subcutaneous tissue in the last group. In children and adults the extension of the forearm displaces entirely the integument which is partially dislocated in old people, resulting in the modification of the furrow direction. The diminution of line density and the increase of spaces between them could easily be observed in microtopographic photographs of the aged skin surface.

3O 20- 10- LINE DENSITY 'T T DEPTH eeeoj eeeoj eeee I eeee I eeee I ©ooo! r41, 4p ,I, ol I 1T m Figure 9. Line density and mean depth of furrows from secondary axis in each group: I--children II--adults Ill--aged people. 60 -40 -20 1,20 1.15 1.10 I II Figure 10. Coefficient of developed skin surface in: I--children II--adults Ill--aged people.