Immunohistochemical and Electron Microscopic Study on the Epidermis of Human Fetus

Kim, Han UK; Park, Sung Sik

Abstract

To identify the developmental characteristics of fetal skin, the expressions of cytokeratine (CK) and epidermal growth factor (EGFR) in fetal skin (12-24 weeks of gestation) were studied immunohistochemically, and the ultrastructure of epidermis was also observed. The Expressions of CK and EGFR were identified in labelled sterptoavidine biotin immunohistochemical method. Primary antibodies used monclonal mouse anti-human CK (DAKO-CK, MF116) and EGFR Ab-4 which is rabbit affinity-purified polyclonal antibody raised against the amino acid residues 1005-1016 (Onc Science). At 12 weeks of gestation the epidermis was composed basal layer and periderm and the cells of both layers were positively stained for CK and EGFR. At 16-18 weeks of gestation, epidermis was composed basal, intermediate, and periderm. The cells of basal layer and periderm were strongly positive for CK, but the cells of intermediate layer showed weak or negative reaction for CK. EGFR immunoreactivity was noted in cells of all three layers, though cells of basal layer were stained relatively weak. At 23-24 weeks of gestation, the epidermis thickened and appeared 6 or more cell layers. Epidermal cells except horny layer were stained positively for CK and EGFR. EGFR immunoreactivity in basal layer, however, was relatively weak compared to those in intermediate layers. Periderm always were reaction-positive for CK and EGFR. The hair follicles, mainly pre-germ stage, were negatively stained for CK and EGFR at 12 weeks of gestation. The hair follicles with various developing stages were positively stained at 16-18 weeks of gestation. At 24 weeks of gestation, inner sheath of hair shaft and sebaceous gland were strongly reacted for CK, but not reacted for EGFR. In electron microscopic study, epidermis was composed of two layers, basal layer and periderm at 12 weeks of gestation. The periderm was composed of basal, intermediate and periderm at 12 weeks of gestation. The periderm was composed of basal, intermediate and periderm layers at 16-18 weeks of gestation. Intermediate cells consisted of 2-3 layers of spinous cells. The granular cells appeared rarely in superficial cells of intermediate layers. At 23-24 weeks of gestation, epidermis consisted of basal, prickle, granular, and horny layers. Periderm cells were locally exfoliated from the hony layer. The results demonstrate the expression of CK and EGFR in skin of human fetus between 12 and 24 weeks of gestation, and suggest that full thickness of epidermis is formed by 24 weeks of gestation.