Studies in the Histogenesis of the Epidermis

INQUIRY into the pathogenesis of epitheliomata reveals an apparent paradox in the activities of the epidermal cells. If we consider the basal cells as the parent cells of the prickle cells, then we have the more primitive cell giving rise to the less malignant tumor. In order to understand this inconsistency we have attempted to reinvestigate the histogenesis of the epidermis, seeking to find just what cellular transitions occur between the primitive ectoderm and the definitive epidermis. We started with a review of the past observations on the development of embryonal skin, then we reviewed the published reports on cellular proliferation in the mature epidermis, and, last, we have recorded our observations of sections of the skin of early pig embryos. In subsequent reports we hope to present studies now in progress upon the skin development in later pig embryos and in human embryos. In the past it was generally