Activities of glycogen synthetase and glycogen phosphorylase in the human endometrium: relative distribution in isolated glands and stroma.

The activities of glycogen synthetase and glycogen phosphorylase were studied in endometrial samples obtained from 51 premenopausal women during the menstrual cycle. The total activities of glycogen synthetase and glycogen phosphorylase and the activity of the active form of glycogen phosphorylase increased gradually from the proliferative phase to the secretory phase and reached a maximum during the midsecretory phase, while the activity of the active form of glycogen synthetase increased slightly. In 30 of the 51 women, the relative distribution of glycogen synthetase and glycogen phosphorylase activities in isolated glands and stromal cells was determined following collagenase digestion of the endometrial specimens. The results indicated that the activities of the active form of glycogen synthetase and glycogen phosphorylase in the isolated glands during the secretory phase were more than threefold and twofold, respectively, greater than those present in the isolated stromal cells and that the levels of these enzymes in the glands and stromal cells changed in parallel with those in the undissociated endometrium observed during the menstrual cycle. In addition, histochemical studies revealed the presence of glycogen phosphorylase activity in both the glands and the stromal cells, whereas the glycogen synthetase activity was present only in the glands. These findings suggest that the stromal cells of the human endometrium as well as the glands may play an important role in the nutrition of the implanting blastocyst.