The purpose of this article is to discuss the structure and function of neonatal skin. In so doing, an attempt will be made to review and condense an enormous body of information to provide a scientific basis for proper care of the neonate/infant and to aid formulators in the development of personal products to assist in that care.
The structure of adult human skin is shown in Figure 1. Skin development involves tissues mainly of mesodermal/ neural crest (body dermis/head dermis) and ectodermal (epidermis) origin. Interaction of these tissues is necessary for differentiation of the epidermis to form the stratum corneum (SC), the barrier contained within, as well as skin appendages, (i.e., hair follicles, sebaceous glands, etc.) Skin development has been classified according to well-defined embryonic/fetal developmental stages.1 These stages comprise: the embryonic period (5-8 weeks); the embryonic/fetal transition period (9-10 weeks); the early fetal period (11-14 weeks); the midfetal period (15-20 weeks); and the late fetal period (20 weeks to birth). (See Figure2, page 63.)
It is in the late fetal period that skin becomes functional (i.e., develops a protective barrier within the SC). Maturation of the barrier is important for the health of the preterm as well as the full-term infant.