Ontogeny of the Epidermal Barrier to Water Loss in the Rat: Correlation of Function with Stratum Corneum Structure and Lipid Content

Abstract

ABSTRACT. The mammalian epidermal permeability barrier is provided by highly hydrophobic lipids forming multiple membrane bilayers within the extracellular domains of the outer, cornified cell layers. To characterize the critical events associated with barrier maturation, we correlated the emergence of a competent barrier to transepidermal water loss with development of the lamellar body secretory system, the organization of stratum corneum membrane bilayers, and the lipid composition of these membranes in the perinatal rat. The primary function of mammalian epidermis during terrestrial life is the generation and maintenance of a competent bamer

Neonatal Development of the Stratum Corneum pH Gradient: Localization and Mechanisms Leading to Emergence of Optimal Barrier Function

“…Newborn pups were removed individually from the litter, in approximately 24 h intervals following birth. Fetal tissue samples were generated by cesarean section, as described earlier (Aszterbaum et al, 1992). 2 0 ,7 0 -bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF) was from molecular probes (Eugene, OR).…”

“…Rats have served as a useful model to examine a range of parameters of the peri-and neonatal adaptation process (Aszterbaum et al, 1992;Hoath et al, 1993;Wickett et al, 1993;Hanley et al, 1997). These studies have shown that the epidermal permeability barrier develops late in gestation, paralleled by increased expression of pH-dependent, lipid-processing enzymes.…”

Complete Cytolysis and Neonatal Lethality in Keratin 5 Knockout Mice Reveal Its Fundamental Role in Skin Integrity and in Epidermolysis Bullosa Simplex

“…Earlier investigations had shown that the time course of skin barrier formation allowed the analysis of correlative changes in epidermal morphology (Aszterbaum et al, 1992). To validate our observations of an unaltered suprabasal development in the absence of K5, we performed a dye permeability Figure 6.…”

Hormonal basis for the gender difference in epidermal barrier formation in the fetal rat. Acceleration by estrogen and delay by testosterone.

“…Although lung surfactant contains predominantly phospholipids, a class of lipids absent from barrier lipids, both secretory systems deliver lipid to their respective extracellular domains (1)(2)(3)(12)(13)(14). Moreover, the epidermal and lung lamellar secretory systems exhibit striking similarities in their developmental timetables, with both maturing in the third trimester in humans and other animals (4,(8)(9)(10)(11)15). In the fetal rat, lamellar bodies first appear in skin and lung on gestational d 18; secretion begins on d 19 and 20, respectively; and maturation of both tissue systems is complete by d 21 of gestation (normal parturition occurs on d 22) (15,16).…”

“…Moreover, the epidermal and lung lamellar secretory systems exhibit striking similarities in their developmental timetables, with both maturing in the third trimester in humans and other animals (4,(8)(9)(10)(11)15). In the fetal rat, lamellar bodies first appear in skin and lung on gestational d 18; secretion begins on d 19 and 20, respectively; and maturation of both tissue systems is complete by d 21 of gestation (normal parturition occurs on d 22) (15,16). Furthermore, glucocorticoids and thyroid hormone accelerate lung maturation (reviewed in reference 17), and, as we have shown, glucocorticoids accelerate epidermal barrier maturation in utero in the rat (18), and both glucocorticoids and thyroid hormone accelerate fetal rat barrier formation in vitro (19).…”