title: Epidermal ridge formation in the human fetus: a correlation to the appearance of basal cell heterogeneity and the expression of epidermal growth factor receptor and cytokeratin polypeptides in the epidermis.
abstract: This paper aims to clarify an expression of epidermal growth factor receptor (EGFR) and cytokeratin 10 and/or 11 in relation to primary and secondary epidermal ridge formation of the human fetus. Firstly, scanning electron microscopy revealed heterogeneity in basal cell morphology during epidermal ridge formation. Basal cells had a uniform, smooth, and polygonal dermal surface until formation of the primary epidermal ridges. Thereafter, the dermal surface became ruffled and elliptic except at the primary epidermal ridges. Secondly, EGFR was detected by monoclonal antibody and autoradiography using 125I-EGF. The antibody reacted with primary epidermal ridge, stratum basale, stratum intermedium, and outer layer of sweat duct. The reactivity became stronger at the primary epidermal ridge than at the secondary one. The binding of 125I-EGF was concentrated in the primary epidermal ridge and sweat duct. Thirdly, cytokeratin 10 and/or 11, a maturation marker of keratinocytes, was detected by monoclonal antibody. The antibody reacted only with the stratum intermedium before secondary epidermal ridge formation. Afterward, it also reacted with the stratum basale of the secondary epidermal ridge but never reacted with that of primary epidermal ridge. The results indicate that basal cells of the secondary epidermal ridge enter the maturation process and suggest a localization of epidermal stem cells on the primary epidermal ridges. Concerning epidermal ridge formation, we suppose that the formation of the primary epidermal ridge causes the segregation of the epidermal stem cells, and that the increased density of the basal cells between the two primary epidermal ridges brings about the change in their dermal surface shape and the formation of the secondary epidermal ridge.
authors.affiliation: Saga Medical School, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Misumi
authors.forename: T
authors.initials: T
authors.lastname: Akiyoshi
mesh_terms: D002454:Cell Differentiation; D004817:Epidermis / Q000737:chemistry / Q000196:embryology*; D066246:ErbB Receptors / Q000032:analysis*; D005333:Fetus / Q000196:embryology; D005385:Fingers / Q000196:embryology; D006801:Humans; D007633:Keratins / Q000032:analysis*; D013234:Stem Cells / Q000648:ultrastructure
chemical_list: D007633:Keratins; D066246:ErbB Receptors