title: Hyperstimulation affects vascular permeability at implantation sites in the rat endometrium.
abstract: OBJECTIVE
  It has previously been shown that deleterious changes occur in the epithelium and stroma of the endometrium of the rat following ovarian hyperstimulation by exogenous gonadotropins. The purpose of the present study was to investigate the formation of possible implantation sites following hyperstimulation. Female rats (n = 8) were injected in phase with their estrous cycle with follicle stimulating hormone (FSH), followed by human chorionic gonadotropin (hCG), and mated at proestrous. Control rats (n = 6) were uninjected and mated at proestrous. Animals were killed at 5.5 days of pregnancy. The pontamine blue technique was used to demonstrate the permeability of the uterine vessels. Implantation sites were demonstrated in the uterine horns of all control animals by segmental blue banding.
  
  
  RESULTS
  Blue staining occurred only in a portion of one horn of one hyperstimulated animal. While fenestrations were found in the walls of capillaries of control animals, similar fenestrations were not observed in the vessels of hyperstimulated animals.
  
  
  CONCLUSIONS
  As the walls of vessels in the hyperstimulated animals failed to become permeable, and as no implanting embryos were found in these animals, it is concluded that there was an inability of the endometrium to form implantation sites. These changes may impede attachment and implantation of the embryo.
authors.affiliation: Department of General Anatomy, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: B
authors.initials: B
authors.lastname: Kramer
authors.forename: A
authors.initials: A
authors.lastname: Magan
authors.forename: G
authors.initials: G
authors.lastname: de Wet
mesh_terms: D000818:Animals; D002199:Capillary Permeability / Q000187:drug effects; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D010064:Embryo Implantation / Q000187:drug effects; D004717:Endometrium / Q000098:blood supply* / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D005260:Female; D006801:Humans; D008297:Male; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D006063:Chorionic Gonadotropin