Lymphocyte number and distribution in the rat uterine epithelium during estrous cycle and early pregnancy

Abstract

The number of intraepithelial lymphocytes (IEL) in the luminal and glandular epithelium of the uterus of virgin rats was analysed in diestrus, proestrus and estrus, and in nulliparous rats on days 5, 7 and 9 of pregnancy. IEL number was calculated either with respect to the number of epithelial cells or to the length of epithelium section. It was found that in diestrus, the number of IEL was, on average, 3.7 per 100 luminal epithelial cells or 6.7 per 1 mm of epithelium section, whereas in proestrus, it decreased to 0.9 and 1.2 IEL, respectively. On day 5 of pregnancy (before implantation) the number of IEL decreased further to 0.45 per 100 luminal epithelial cells or 0.9 per 1 mm of epithelium. On days 7 and 9 of pregnancy, IEL number further decreased in implantation sites, whereas in interimplantation sites it remained at the level calculated for day 5 of pregnancy. The population of uterine IEL consisted of small (82-99%) and large (1-18%) lymphocytes. In all stages of the estrous cycle, IEL occurred with a frequency of 68-87% in the basal region, 8-20% in the middle region and 4-12% in the apical region of the luminal epithelium width.

Establishment of a mouse primary co-culture of endometrial epithelial cells and peripheral blood leukocytes: Effect on epithelial barrier function and leukocyte survival

“…We based our current study on the ratios of immune cells to epithelial cells in the vagina of a rat, as reported by another study. The other study suggested that there was 1 immune cell per 100 epithelial cells (1:100) in the vagina of a rat under homeostasis, but this ratio quickly changes to 10 immune cells per 100 epithelial cells during bacterial infections (1:10) in the vagina (Sawicki et al, 1988). Based on this information, the EEC and PBL seeding ratio was determined to be 1:3 (PBL:EEC) during the initial cell culture, taking into account that EEC, but not PBL, will proliferate after 4 days to give a final ratio of approximately 1:10.…”

“…Other studies of the mucosa have shown the existence of immune cells in between epithelial cells of the endometrium of rats (Pace et al, 1991), including T-lymphocytes, B-lymphocytes, monocytes, macrophages, dendritic cells, neutrophils and intraepithelial lymphocytes (IELs). These cells exist in low numbers in normal endometrium during homeostasis, and their numbers can vary during different stages of the estrus cycles (Sawicki et al, 1988). Upon bacterial infections, cell recruitment to the site of the infection increases the number of immune cells in the epithelium.…”

Reduction in endometrial neutrophils in proximity to implanting rat blastocysts

“…A number of studies have demonstrated characteristic distribution patterns for rat uterine leucocytes during the oestrous cycle and early pregnancy (Lobel et al, 1967;Tachi & Tachi, 1986;Sawicki et al, 1988;Noun et al, 1989). Taken together, this work clearly shows that endometrial leucocyte populations are closely controlled and that these control mechanisms are under the influence of oestrogen and progesterone.…”

“…One cell type that often plays a major role in initiating the inflammatory response is the circulating polymorphonuclear leucocytic neutrophil (Wedmore & Williams, 1981). Although there have been many reports of leucocyte distribution in the endometrium during the peri-implantation period (Lobel et al, 1967;Tachi & Tachi, 1986;Sawicki et al, 1988;Noun et al, 1989), there has only been one quantitative investigation of endometrial neutrophil distribution at this time (Finn & Pope, 1991); and from that study in mice, it was concluded that during the early stages of decidualization, shortly after the increase in microvascular permeability has commenced, there is an attraction of neutrophils from the blood into the endometrial stroma. This observation raises the possibility that neutrophils may mediate part of the endometrial response to the implanting embryo.…”

Ultrastructural Changes in the Uterine Luminal and Glandular Epithelium during the Oestrous Cycle of the Marsupial <i>Monodelphis domestica</i> (Grey Short-Tailed Opossum)

“…Early responses to oestrogen in the uterus of rodents include changes in vascular permeability, cellular infiltration and water uptake in the stroma [Yanagimachi and Chang, 1963;Sawicki et al, 1988;Perez et al, 1996]. The number of intraepithelial leucocytes and the time of their maximum appearance seem to be species dependent.…”