Effect of single-dose, early luteal phase administration of mifepristone (RU486) on implantation stage endometrium in the rhesus monkey

Debabrata Ghosh, Jayasree Sengupta, Andrew G Hendrickx

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50 Scopus citations


The characteristics of implantation stage endometrium following a single-dose, early luteal phase application of mifepristone (RU486) in proven conception cycles has been examined in the rhesus monkey in an attempt to understand the physiological basis of the anti-implantation activity of the drug. Endometrial samples were collected from monkeys subjected to vehicle (group 1, n = 14) and RU486 (2 mg/kg body weight; group 2, n = 12) on day 2 after the presumed day of ovulation of successfully mated cycles. The average diameter of glands (P < 0.05), number of vacuolated cells (P < 0.01), number of supranuclear vacuolated cells (P < 0.05) in glandular epithelium and amount of glandular secretion (P < 0.05) were significantly lower in RU486-treated endometrium compared with control tissue samples. Additionally, 18% of glandular epithelial cells showed apoptotic and degenerative features in RU486-treated tissue samples. These data, together with the observed significant decreases in precipitate area (P < 0.02) and in the optical absorbance of alkaline phosphatase reaction end-product (P < 0.05), confirm that retardation in glandular differentiation in the upper functionalis is a likely target of antiprogestin action in implantation stage endometrium. An increased frequency of mitosis in stromal cells (P < 0.05) and a greater degree of extravasation (P < 0.05) were also observed after RU486 exposure. Despite an apparent indication of constriction and regression in few RU486-exposed endometria compared with controls, morphometric analyses did not show any changes in capillary structure. Whether endometrial vasculature in progesterone-exposed uterus is a target of antiprogestin action during the peri-implantation stage remains to be determined. Further studies are required to explain the observed increase (P < 0.02) in the area of precipitate of von Willebrand (vW) factor with no change in vW factor-positive vessels, and the apparent increase in collagen IV immunostain in subepithelial and perivascular basement membrane in implantation stage endometrium after early luteal phase RU486 treatment in monkeys.

Original languageEnglish (US)
Pages (from-to)2026-2035
Number of pages10
JournalHuman Reproduction
Issue number9
StatePublished - Sep 1996


  • Endometrium
  • Monkey
  • Preimplantation stage
  • RU486
  • TEM

ASJC Scopus subject areas

  • Physiology
  • Developmental Biology
  • Obstetrics and Gynecology
  • Reproductive Medicine


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