Endometrial biopsy cytology
Keywords: biopsy, equine, endometrium, uterus, infertility
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This image shows margination of neutrophils (PMN) during estrus. This is a common phenomenon seen in endometrial biopsies especially but not exclusively during standing heat. Neutrophils attach to the endothelium of the capillaries in the lamina propria and migrate into the stroma. This is thought to augment uterine defenses during breeding. Also seen in this image are some marginating eosiniphils (E). They are commonly seen in the stroma of equine endometrial biopsies and although they have been associated with the "wind-sucking" condition, this is poorly substantiated.
The capillary containing these cells is surrounded by endometrial glands with lumens that are not obvious.
The image below shows the typical appearance of lumen epithelial cells during estrus. They are significantly taller than the same cells epithelial cells during diestrus (the luteal phase). Also note the cilia. They are dispersed intermittently across the surface of the epithelium. On a scanning electron micrograph they appear like tufts of grass on a barren lawn. Between the "tufts of grass" are the intermittent openings of endometrial glands.
Image size: 990 x 630px
Hemosiderin is commonly found in macrophages in endometrial biopsies. Evidence of this is shown below. The presence of hemosiderin, which usually remains in the endometrium for long periods of time, usually reveals that a mare has experienced intrauterine hemorrhage sometime in her life. Although there is practically no overt hemorrhage from the endometrium during or after foaling, mild hemorrhage is likely. Therefore endometrial hemosiderosis probably indicates that a mare has had one or more foals in her lifetime.
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Plasmacytes and lymphocytes are common "janitorial cells" in the lamina propria, especially the stratum compactum as shown below. On occasion, even highly experienced pathologists may have difficulty distinguishing between these two types of cells. They provide local immunity in the endometrium and unless they are present in large numbers should not be interpreted as an indication of chronic endometritis.
