An ultrastructural study of interstitial implantation in captive-bred, short-tailed fruit bats, Carollia perspicillata : trophoblastic adhesion and penetration of the uterine epithelium

Abstract

Trophoblastic adhesion to, and penetration of, the uterine epithelium during implantation have been examined in captive-bred Carollia perspicillata at the light and electron microscopic levels. Initial adhesion is localized to marginal ridges immediately over the apical intercellular junctions of the epithelial cells. Penetration then involves the intrusion of trophoblastic processes between the epithelial cells and the formation of junctional complexes between the two cell types. As larger areas of adhesion develop, they still occur most often near the intercellular boundaries between the more flattened epithelial cells or on their lateral sides. This suggests that many (if not all) of these broad areas of adhesion to the trophoblast had actually formed along what had originally been part of the lateral (rather than the apical) surfaces of the epithelial cells. Portions of the apical cell surfaces further removed from their intercellular boundaries usually were not adherent to the trophoblast and still had microvilli. Upon reaching the basal lamina of the uterine epithelium, invasion of the endometrium is temporarily retarded, and trophoblast cells migrate instead between the basal lamina and the epithelial cells. This occurs extensively along both the luminal and glandular epithelia around the implantation site, but not significantly along their apical surfaces. This again indicates that adhesive interactions between the trophoblast and those apical surfaces are at most very limited in Carollia. The epithelial cells appear to be viable until separated from their basal laminae by the trophoblast. They are then phagocytized by the trophoblast. During initial penetration of the uterine luminal epithelium, the trophoblast is still entirely of the cellular variety. Syncytiotrophoblast does not begin to appear until later, when the trophoblast first comes into contact with endometrial capillaries.

Selectivity in the transport of spermatozoa to oviductal reservoirs in the menstruating fruit bat, Carollia perspicillata

“…Although this blastocyst appeared normal (cf. Badwaik et al 1997, Rasweiler et al 2002, an unusual dilatation of the IUC was evident beneath the implantation site. The associated CL was in the right ovary.…”

Relación Útero-Embrionaria Y Su Variación Morfológica Durante El Período Implantacional en Conejo

“…Pero la penetración inicial en este animal, al compararlo con estudios realizados en ratón por Larsen, (1961), no es pasiva. Estudios en rata, (Enders & Schlafke, 1969), y en murciélagos Carollia por Rasweiler et al, 2002, describen que después de la invasión inicial del epitelio uterino luminal por las células trofoblásticas, éste permanece por un tiempo adyacente a la lámina basal residual del epitelio, pero no lo penetra. Murphy et al (1982) observaron alteraciones estructurales en las células endometriales, por lo que deducimos que la implantación es más invasiva en roedores murinos que en conejo.…”

Embryonic diapause in the short-tailed fruit bat, Carollia perspicillata: why this is postimplantational

“…Carollia initially became of interest, because it exhibits multiple female reproductive similarities to humans. These include being monovular, having a simplex uterus, exhibiting true menstruation, displaying interstitial implantation of the blastocyst in a preferred portion of the uterus, and having highly invasive trophoblast [10,12,13]. During the course of efforts to more fully evaluate the species' potential utility as a model for the study of human reproduction, it was noted that some other aspects of its reproductive biology are quite unusual.…”