title: Nexus formation in the myometrium during parturition and induced by estrogen.
abstract: The occurence of nexuses (gap junctions) in mouse uterine smooth muscle was found to depend on the hormonal state. As revealed by freeze-fracture electron microscopy, nexuses are virtually absent in virginal and pregnant mice. Abundant, large-sized nexuses were observed in the myometrium during parturition. Estrogen application to virginal mice also induced an increase in number and size of nexuses. Our observations indicate that a new formation of nexuses occurs in differentiated cells. New nexuses may be formed by the confluence of nexus subunits preexisting in the cell membrane or by newly biosynthesized components.
mesh_terms: D000818:Animals; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D005614:Freeze Fracturing; D007365:Intercellular Junctions / Q000648:ultrastructure*; D007743:Labor, Obstetric; D051379:Mice; D009215:Myometrium / Q000187:drug effects / Q000648:ultrastructure*; D011247:Pregnancy; D014599:Uterus / Q000648:ultrastructure*
chemical_list: D004958:Estradiol