[Studies on the activities of glycogen synthetase and glycogen phosphorylase in the human endometrium (author's...

Glycogen content, glycogen synthetase and glycogen phosphorylase were studied in the endometrial tissues of 28 women with normal menstrual cycles and in the decidual tissues of 24 women with normal early pregnancies. The endometrial glycogen synthetase enzyme increased gradually from the proliferative phase to the secretory phase and reached maximal activity during the sixteenth to twenty-third days of the cycle, a time coincident with maximal glycogen content, while the glycogen phosphorylase reached its maximal activity on and after the twenty-fourth day of the cycle. In addition, glycogen phosphorylase activity in the decidual tissue during the early period of gestation (4--10 weeks) was lower than that in the endometrial tissue during the late secretory phase of the cycle, and in particular, the active form (-AMP) was significantly (p less than 0.005) low, with the result that the glycogen content in the decidua was significantly (p less than 0.05) higher than that in the endometrium. On the other hand, in 20 normal pregnant women during the 6--10th weeks of gestation, the glycogen contents in the decidua and in the placental villi were 599 +/- 44 mg/100 g wet weight (mean +/- standard error of the mean) and 731 +/- 55 mg/100 g, respectively, but the difference between them was statistically not significant. The levels of glycogen synthetase and glycogen phosphorylase enzyme in the decidua were significantly (p less than 0.005) higher than those in the placental villi.