This study presents a comparative analysis of the histogenesis of thick and thin skin in human fetuses, emphasizing the morphological differences between the epidermis, dermis, and the development of eccrine sweat glands. Skin samples from the hands and feet of four fetuses at 19 weeks of gestation were histologically analyzed, evaluating both the dorsal and ventral regions using conventional histological stains and collagen fiber analysis. The results reported here show that epidermal thickness in both the palmar and plantar regions is significantly greater than in dorsal areas, showing statistically significant differences. In thick skin zones, well-defined dermal papillae and epithelial buds at various stages of glandular development were observed. In the palmar and plantar papillary zones, type III collagen fibers were arranged perpendicularly to the epidermis, while in the reticular zone, type I collagen was found in association with blood vessels and nerves. It is concluded that the fetal skin already shows functional regionalization at this stage of the gestational period, evidencing differential maturation in areas that will be subject to greater postnatal friction. These findings are relevant to perinatal medicine, as they provide key information on the formation of the cutaneous barrier in premature neonates and their increased susceptibility to dehydration and infections.
KEY WORDS: Human fetal skin; Human eccrine glands; Human fetal dermis; Human epidermis-dermis.
