Abstract

To observe developing process of human fetal skin during intrauterine life, morphological studies in light microscopic level were made based on 27 human embryos and 76 fetuses ranging from 4 to 40 gestation weeks. The fetuses were the products of induced abortion and were found to have no associated diseases of congenital anomalies at the autopsy. Ten different portions of the body were sampled and examined. They were scalp, forehead, face, chest, abdomen, back, palm, sole, finger and toe. In embryos two different portions; cephalic and caudal portions were examined: The following results were obtained: 1) A single layer of undifferentiated cell was the primitive epidermis at the 4th week and it was followed by two layered epidermis consisting of periderm and primitive basal cell layer. Epidermal ridges started to develop along with primitive eccrine and hair germs as clustering of basal cells at the llth week. Stratum inter-medium was formed at the 12th week, and primitive granular cell layers and keratin formation in association with hair follicles at the 19th week forming earliest adult type epidermis, followed by progressive maturation. 2) The thickness of the fetal epidermis and keratin layer increased as the fetal age approached to the term with its slightly different developmental pattern by the site of body. Cephalic protions developed slightly earlier than the other parts. 3) The developmental pattern of various portions of epidermis could be categorized into three groups; (1) scalp, forehead and face; (2) chest, abdomen and back; (3) palm, sole, finger and toe.

• Keywords: Fetal skin;Epidermis;Keratin layer;Periderm;