title: Gap junction formation in the human uterine muscle cell of the corpus and cervix during the menstrual cycle and pregnancy.
abstract: The difference between sex steroid hormone dependency on gap junction (GJ) formation in human uterine muscle cells of the cervix and corpus was investigated using electron microscopic morphometry and steroid hormone radio-immunoassay. The results obtained are summarized as follows: The number of GJ in human uterine cervical muscles changed during the menstrual cycle and became greater in the periovulatory phase, whereas the GJ of myometrial muscle changed little in number during the menstrual cycle. During pregnancy, the number of GJ in myometrial muscle increased at delivery (before labor v.s. during labor 8.1 +/- 0.6 v.s. 12.8 +/- 1.0, n = 7-2, p less than 0.01), while the number of GJ in the cervix showed no significant change. When the number of myometrial as well as cervical muscle GJ around the third trimester was compared to that of the nonpregnant (luteal phase) status, there was a significant increase in the number of GJ (luteal phase v.s. during labor 6.6 +/- 1.2 v.s. 12.8 +/- 1.0, p less than 0.05 in the myometrium and 4.6 +/- 1.0 v.s. 9.6 +/- 0.7, p less than 0.05 in the cervix). This increase in the number of myometrial GJ correlated well with the increase in the circulating E2 to P ratio (r = 0.75, p less than 0.001), whereas a slight correlation was found between cervical GJ and these levels (r = 0.42, p less than 0.05). The results of the present study support the hypothesis of an estrogen-dependent formation of myometrial muscle GJ, although the current observations of the human cervix continue to raise the question whether or not identical mechanisms may operate in the cervix.
mesh_terms: D002450:Cell Communication; D002584:Cervix Uteri / Q000166:cytology*; D003338:Corpus Luteum / Q000166:cytology*; D004958:Estradiol / Q000097:blood / Q000502:physiology; D005260:Female; D006801:Humans; D007365:Intercellular Junctions / Q000502:physiology*; D008597:Menstrual Cycle; D009215:Myometrium / Q000166:cytology*; D011247:Pregnancy / Q000502:physiology*; D011374:Progesterone / Q000097:blood / Q000502:physiology
chemical_list: D011374:Progesterone; D004958:Estradiol