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

Hwang, Sang Min; Kim, Dong Kun

Abstract

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.