Changes in vascular permeability and deciduoma formation during the peri-implantation period of the rat in response to exogenous gonadotropins.

Abstract

Permeability of thin-walled vessels of the endometrium could be a prerequisite for deciduoma formation. Exogenous gonadotropins alter endometrial morphology and inhibit vascular permeability on the day of implantation. The aim of this study was to investigate the effect of exogenous gonadotropins on vascular permeability in the peri-implantation period and relate this to deciduoma formation. Female rats were hyperstimulated with follicle-stimulating hormone and human chorionic gonadotropin prior to mating. Control animals were not injected. Endometrial tissue was collected at 4.5, 5.5, and 6.5 days after mating. Tissue was processed for electron microscopy. The presence of thin-walled fenestrated vessels and decidualised stromal cells were found in all control groups. With the exception of one fenestration, which occurred in a vessel from one hyperstimulated animal on 5.5 days of pregnancy, no fenestrations were found in the vessels of hyperstimulated animals. Decidualisation of stromal cells did not occur in these animals. Hyperstimulation with exogenous gonadotropins inhibits vascular permeability and subsequent decidualisation. Implantation thus fails to occur.