title: [Concentration of estrogen and progesterone receptors in the lower uterine segment at term labor].
abstract: BACKGROUND
  To determine cytosol estrogen and progesterone receptor concentrations in the human lower uterine segment in different stages of cervical dilatation during parturition at term.
  
  
  METHODS
  Biopsy specimens of the lower uterine segment were obtained from 51 women undergoing non-elective cesarean section at term. The stage of cervical dilatation at the time of cesarean section was < 2 cm (N = 14), 2 to < 4 cm (N = 13), 4 to 6 cm (N = 11) or > 6 cm (N = 13). The cytosolic estrogen and progesterone receptor concentrations were determined by enzyme immunoassays.
  
  
  RESULTS
  Median estrogen receptor concentrations at < 2 cm and at 2-< 4 cm cervical dilatation were 2.12 fmol/mg protein and 2.03 fmol/mg protein, respectively. After a significant drop at 4-6 cm cervical dilatation (median: 1.08 fmol/mg protein), estrogen receptor concentrations raised again at > 6 cm cervical dilatation (median: 2.00 fmol/mg protein). Median progesterone receptor concentration was 84.7 fmol/mg protein at < 2 cm cervical dilatation, diminished significantly at 2-< 4 cm cervical dilatation (36.6 fmol/mg protein) and increased at further cervical dilatation (4-6 cm: 75.7 fmol/mg protein; > 6 cm: 83.7 fmol/mg protein).
  
  
  CONCLUSIONS
  These data suggest that predominantly a decrease in cytosolic concentration of the progesterone receptor at the beginning of the active phase of first stage labor may play a crucial role in the hormonal control of cervical dilatation during parturition at term.
authors.affiliation: Frauenklinik für Gynäkologie und Geburtshilfe, Universitätsklinikum der Rheinisch-Wesffälischen Technischen Hochschule Aachen. mwinkler@post.klinikum.rwth-aachen.de
authors.forename: M
authors.initials: M
authors.lastname: Winkler
authors.forename: S
authors.initials: S
authors.lastname: Zlantinsi
authors.forename: B
authors.initials: B
authors.lastname: Kemp
authors.forename: J
authors.initials: J
authors.lastname: Neulen
authors.forename: W
authors.initials: W
authors.lastname: Rath
mesh_terms: D000328:Adult; D001706:Biopsy; D002585:Cesarean Section; D003600:Cytosol / Q000473:pathology; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007747:Labor Stage, First / Q000502:physiology; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D011960:Receptors, Estrogen / Q000032:analysis*; D011980:Receptors, Progesterone / Q000032:analysis*; D012016:Reference Values; D014599:Uterus / Q000473:pathology*
chemical_list: D011960:Receptors, Estrogen; D011980:Receptors, Progesterone