抄録
To characterize the perifollicular sheath of the human scalp hair follicle, morphological features, growth pattern, the effect of dihydrotestosterone on growth behavior, and levels of 5α-reductase type I, 5α-reductase type II, aromatase, 17β-hydroxysteroid dehydrogenase, and androgen receptor mRNAs were compared in perifollicular sheath cells, dermal papilla cells, and nonfollicular dermal fibroblasts. Perifollicular sheath cells displayed a similar flattened morphology and the same aggregative trait as dermal papilla cells, but differed from nonfollicular dermal fibroblasts. Perifollicular sheath cells grew faster than dermal papilla cells but slower than dermal fibroblasts. Dihydrotestosterone at concentrations of 30 ng/ml and 300 ng/ml significantly reduced the growth rate of perifollicular sheath cells, whereas dihydrotestosterone had no effect on nonfollicular fibroblasts or dermal papilla cells. The perifollicular sheath of the follicle was clearly stained with an antibody against α-smooth muscle actin, but dermal papilla cells within follicles were not stained. However, a large percentage of both dermal papilla and perifollicular cells in culture were stained by this antibody. Nonfollicular fibroblasts were moderately stained by this antibody. Perifollicular sheath cells and dermal papilla cells contained similar levels of 5α-reductase type I, 5α-reductase type II, aromatase, 17β-hydroxysteroid dehydrogenase, and androgen receptor mRNA. These results provide evidence that the perifollicular sheath and the dermal papilla form a functional unit distinct from the surrounding nonf ollicular connective tissue.
