Histopathology of endometrial glands in healthy, metritic and septic metritic cows at 5–10 days post-partum. Scale bars in all images are 50 µm. Healthy cows: A, B H&E stained sections, showing well preserved endometrial glands with columnar epithelium. C Blue MPO immunohistochemistry with red Sytox orange counterstain shows PMN presence mainly in blood vessels. Metritic cows: D, E H&E stained sections show preserved endometrial glands. Epithelial cell morphology is predominantly cuboidal. Infiltrating PMN (green arrowheads) are commonly seen in the epithelial layer and in the gland lumen. F MPO immunohistochemistry shows abundant PMN infiltration. Septic metritic cow: G, H H&E stains show endometrial glands in advanced stages of destruction. PMN infiltration (green arrowheads) can be seen in the epithelial layer and around the glands. I MPO immunohistochemistry shows PMN infiltration to a lesser extent compared to the metritis cows (F).