Prenatal Development of Eccrine Sweat Gland: Morphologic and Morphometric Analysis

ABSTRACT

To elucidate the developmental sequence of the eccrine sweat gland, a morphologic and a morphometric observation were done using developing human embryos and fetuses. Five embryos and sixty four fetuses from the 9th to the 38th week of the gestational age were studied. The skin was sampled in eight different areas, i.e., scalp, forehead, face, chest, abdomen, back, palm and sole. Routine histological sections were made for histological evaluation and morphometric analysis. The results obtained were as follows The primordia of the eccrine sweat glands appeared first as regular undulation of the basal cells in the palm and the sole in the 13th week of getation. Subsequently, elongation and coiling of the cell cords were noted from the 16th to the 18th weeks. Intraductal lumen formation was first noted in the 20th week. Secretory segment of the eccrine sweat glands were noted from the distal part of the coiling intradermal sweat duct in the 22nd week of the gestational age. The eccrine sweat glands became fully developed by the 28th week of gestation and this included the clear cell, the dark cell and the myoepithelial cell. In the morphometric analysis, the number of eccrine epithelial buddings were decreased with aging and the highest were in the palm and the sole. The diameter of the eccrine sweat duct showed no significant change by gestational age or in the different sites observed. Straight and coiled eccrine sweat ducts or glands were lengthened into the deep reticular dermis and upper portion of the subcutaneous adipose tissue with an increase of the gestational age. The above results suggest that developmental stage and the number of eccrine glands of the skin in the fetal stage is different from other areas of the body, especially in the palm and the sole.