To observe the developing process of human fetal eccrine sweat gland during the intrauterine life, an electron microscopic study was carried out based on 12 fetuses ranging from 20 to 42 weeks of gestation. These fetuses were the products of induced deliveries found to have not associated disease or congenital anomalies at the autopsy. Following observations were made.
The various types of cell consisting coiled portion of eccrine sweat gland were recognized at he 20th weed of gestation and they were clear cells, undifferentiated dard cells, myoepithelial cells. clear cells were located in central portion and dark or myoepithelial cells were in peripheral portion. While undifferentiated dark cells were randomly distributed in the straight portion of eccrine ´sweat ´ gland.
The differential points between clear cell and undifferentiated dark cell were its round nucleus and glycogen contents. Marked hydropic changes of clear cells were noted at the 30th week of gestation. Secretory granules were noted at the 31st week of gestation. Secretory cells in the coiled, portion of eccrine swear;, gland was not fully mature until the 42nd week of gestation.
Clear cells showed clear cytoplasm, abundant free ribosomes. and scanty organelles. Undifferentiated dark cells showed many mitochondria and few glycogen. Secretory granules were rarely seen. Myoepithelial cells showed a few mitochondria, glycogen and, microfilaments.
Among three portions of eccrine gland, duct lumen in the aural and coiled portion were formed through the intracellular canaliculus and in the straight portion were made through the intercellular canaliculus. The.main basic morphological mechanism of the lumen formation were microvesicle formation and pinched off phenomenon.
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