Ultrastructural and histochemical changes of the mouse uterine epithelium on blastocyst activation for implantation

摘要

An electron microscopic study was made of the changes of the trophoblast and the uterine epithelium at early implantation. During delay of implantation in mice, only a small amount of secretion was present in the uterine lumen, and the trophoblast-epithelial space was narrow. The luminal part of the uterine epithelial cells contained a 0.1 μm deep layer of dense ground cytoplasm devoid of organelles and inclusions. Below this juxtaluminal layer many apical vesicles were seen. The luminal part of the trophoblast cells contained several endocytic vesicles, indicating that in spite of its low metabolic activity, the blastocyst is actively taking up substances at this stage. This also implies that the uterine epithelium is secreting, although at a low rate. At the luminal surface of the uterine epithelium, however, tests for alkaline phosphatase and glucose-6-phosphatase reactions were negative