Barrier formation in the human fetus is patterned

We recently demonstrated patterned stratum corneum maturation and skin barr ier formation during fetal development in rodents and rabbit. The presence of skin patterning in these mammals led us to predict patterned barrier for mation during human infant development, Here we extend our mammalian study and demonstrate patterned stratum corneum development and skin barrier form ation in the preterm human infant. Surprisingly, we show initiation of huma n barrier regionally as early as 20-24 wk gestational age (22-26 wk menstru al age), bringing barrier format-ion close to the time of periderm disaggre gation. We use the mouse model to show that patterns of periderm disaggrega tion mirrors barrier formation. Periderm disaggregation follows and recapit ulates barrier pattern, suggesting a relationship between the processes. Th is work reveals regional patterning in skin maturation and barrier formatio n in the human infant and demonstrates that initiation of human skin barrie r formation in utero coincides with the current lower limit of viability of the pre-term infant.