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[Study on the relationship between epidermal stem cells and the developing process of sweat gland in human fetal skin].

OBJECTIVE
To explore the relationship between epidermal stem cells and the developing process of sweat gland in human fetal skin, so as to obtain a hint for future induction of epidermal stem cells to differentiate into sweat gland cells.


METHODS
Total layer of human skin from the back of fetus at gestational ages from 11 to 31 weeks, obtained from spontaneous abortion was routinely examined. The expressions of beta1 integrin and keratin 19 in sweat gland cords or buds and mature sweat gland cells were dynamically observed with SP immunohistochemical technique. The development and maturation of sweat gland were identified by the positive staining of keratin 8 with immunohistochemistry.


RESULTS
It was revealed by histologic observation that basal layer cells of the primary epidermal ridge exhibited focal aggregation and formed hillocks at 16 gestational weeks. The hillocks of cells then migrated downward as cords into the dermis during 18 - 20 gestational weeks. Then, the end part of the cell cord developed into a round lump of twining cords assuming the mature sweat gland. The expressions of beta1 integrin and keratin 19 were found not only in sweat gland cords and buds but also in the mature cells and lasted throughout the total period of sweat gland development. The expression of keratin 8 in sweat gland buds started since 14 - 16 gestational weeks and maintained thereafter.


CONCLUSION
The sweat gland started to develop during 14 - 16 gestational weeks and matured at 24 weeks. During the development process of sweat gland, epidermal stem cells were considered to be the key source.