The Changes of Cytokeratin 19 and bcl-2 Expression during Hair Follicle Morphogenesis in Human Fetal Skin / 대한피부과학회지

BACKGROUND: During human skin development, hair follicles dynamically develop to adult hair structures through the hair germ, hair peg and bulbous hair peg. In this perspective, it is thought that the distributions of stem cells changes following the stage of the hair follicle morphogenesis. OBJECTIVE: The purpose of this study was to observe the distribution of stem cells following the stage of hair follicle morphogenesis. METHODS: Skin was obtained from the abdomen skin of 15 human fetuses, ranging from 10 to 23 weeks of gestational age. Immunoperoxidase staining was performed on frozen sections using monoclonal antibodies to cytokeratin 19, known as a stem cell marker, and bcl-2, a factor to prevent cells from entering the apoptotic pathway. RESULTS: 1. Cytokeratin 19 was expressed in the periderm, basal cell layer and condenced cells constituting the hair germ and peg. In the early bulbous hair peg stage, it was expressed in the entire outer root sheath cells, the bulge area and basal cells of the hair bulb. In the late bulbous hair peg stage, it was expressed in the bulge area, outer root sheath cells only of inferior portion and some of the germinative cells of the hair bulb. 2. Bcl-2 was expressed in the basal cells intermittently, condenced cells constituting the hair germ and aggregates of dermal mesenchymal cells concentrating along the hair germ. In the hair peg stage, it was expressed in the entire basal cell layer, condenced cells constituting the hair peg and aggregates of dermal mesenchymal cells along the hair peg. In t.he bulbous hair peg stage it was expressed in the basal cells of the infundibulum, sebaceous gland, bulge area, germinative cells of the hair bulb and the dermal papilla cells. CONCLUSION: From the results obtained, we thought that the distribution of stem cells is dynamically changing following the stages of the hair follicle morphogenesis. It was also speculated that bcl-2 might have an important role in dermoepidermal interactions during hair follicle morphogenesis.

Immunohistochemical Staining of S - 100 Protein in Human Fetal Skin / 대한피부과학회지

The authors attempted to examine the distribution of S-100 protein in the human fetal skin. Immunohistochemical staining(ABC rnethod) using anti-S-100 antibodies was carried out on skin specimens taken from 11 human fetuses ranging from 9 weeks to 27 weeks of estimated gestational age. At 9 weeks of estimated gestational age, the embryonic epidermis consisted of three cell layers,' the basal layer, intermediate layer and periderm, all of them being stained for S-100 protein. But after 18 weeks, the basal layer changed to be negative. Granular and cornified layer's, beginning their development at 22 weeks, were not stained for S-100 protein. Hair germ of 12 week-fetuses was recognized unstained as a bulge of basal cells. In fully differentiated structural components of the hair follicle after 18 weeks, the outer root sheath only was stained for S-100 protein whereas the inner root sheath, hair matrix cells and sebaceous glands were unstained. Eccrine gland germs developed at 12 weeks of embryonic life as undulation of the basal layer and were not, stained. And at 22 weeks, the secretory portion of the eccrine glands were formed in the dermis and stained for S-100 protein. Our present study suggests that the expression of S-100 protein can undergo considerable changes during ernbryonic differentiation in the epidermis and epidermal appendages.