Scanning electron microscopic changes of the canine uterine luminal surface during oestrus and late metoestrus

In this study the endometrial morphology of four dogs in oestrus and 10 dogs in late metoestrus was investigated with scanning electron microscopy. In early oestrus the cells were slightly convex with fairly long microvilli and cell boundaries that were apparent but situated on a deeper level than the cell surface. In late oestrus the cells were clearly convex with long and numerous microvilli masking the cell boundaries. At the beginning of late metoestrus the cells became less convex with many but short microvilli and prominent but lower situated cell boundaries. At the end of late metoestrus the cells were flat with very short microvilli and protruding cell borders. These morphological findings were correlated with the cyclic variations of the steroid hormone levels.