Distribution of PMNs in the bovine CL throughout the luteal phase. Figure 2A-F indicate typical images of PMNs by PAS staining in the CL during the estrous cycle. Black arrows indicate PMNs. PMNs were clear granule and segmented nuclear. As Figure 1A, on day 1-2 and 3-4 of the estrous cycle, high numbers of PMNs were detected within the luteal tissue (Figure 2A and B). Scale bars indicate 50 μm.