Morphology and glycoprotein synthesis of uterine glandular epithelium in human basal plate at term: An ultrastructural and autoradiographic study

This study describes the morphologic features of uterine glandular epithelium in human basal plate at term and identifies this epithelium as an active site of glycoprotein synthesis. Wedge biopsies were obtained from the basal plate at the time of repeat cesarean section from 11 normal pregnant patients at term. Biopsy specimens were either processed immediately for microscopic examination or incubated in vitro with 25μCi/cc of ³H‐galactose or ³H‐leucine. Tissues incubated with tritiated compounds (2‐hour pulse ± 3‐hour chase in nonradioactive medium) were either processed for light microscopic autoradiographic analysis or extracted for determination of trichloroacetic‐acid‐precipitable tritiated macromolecules in tissues and medium. Profiles of cuboidal‐columnar glandular epithelium were identified in the decidual component of the basal plate region adjacent to spiral arterioles and perpendicular to the inner layers of myometrial muscle. Autoradiographic and biochemical studies identified the glandular epithelium, as well as large decidual cells, to be major sites of incorporation of both ³H‐galactose and ³H‐leucine and to be prime sources for secretion of tritiated macromolecules that appeared in the medium during in vitro incubation of basal plate tissue. Ultrastructurally, the glandular epithelium was noted to rest on a basal lamina, to have lateral cell membranes with numerous desmosomes, and to exhibit an apical surface with microvilli projecting into a luminal space. Cytologic features of the cells included abundant profiles of rough endoplasmic reticulum, multiple mitochondria with lamellar cristae, a well‐developed perinuclear but nonpolarized Golgi apparatus, and nuclei containing predominantly euchromatin. Lipid droplets and glycogen deposits were present in some cells. This study indicates that uterine glands persist throughout human gestation in the basal plate and that these glands continue to be active in glycoprotein synthesis and secretion.