CELLULAR CHARACTERIZATION OF ADIPOSE-TISSUE FROM VARIOUS BODY SITES OF WOMEN

Adipose tissue is the primary site of estrogen biosynthesis in postmen opausal women. The two main histologic components of adipose tissue ar e mature adipocytes and fibroblasts. Aromatase P450 expressed in the f ibroblast component of adipose tissue is responsible for catalyzing co nversion of C-19 steroids to estrogens. We previously have demonstrate d that, in women, aromatase expression in adipose tissue of various bo dy sites increases with age and that aromatase expression in the hip i s markedly higher than in the abdomen. To determine whether this age- and regional-dependent variation in aromatase expression is caused by an alteration in the ratio of fibroblasts to mature adipocytes, we col lected sc adipose tissue samples from 19 women (age range: 21-93 yr) a t the time of autopsy. Using a computerized image analysis system, we determined by morphometry the proportions of adipocytes, fibroblasts, and vascular endothelial cells within histologic sections of adipose t issue from midabdomen, both breasts, and both hips. The percentage of each cell component at each body site was expressed as the mean of tri plicate replicates. Statistical analysis of our results did not indica te any correlation between advancing age and fibroblast to adipocyte r atios in the breast, abdomen, or hip. Fibroblast to adipocyte ratios w ere found to be significantly higher in the breast and abdomen compare d with the hip (P < 0.05). No statistical differences were found betwe en the breast and abdomen. These findings suggest that the increase in aromatase expression with advancing age and the higher aromatase expr ession in the hip compared with the abdomen in women may be caused by alterations in specific signal transduction mechanisms rather than a s imple increase in local adipose fibroblast numbers.