Telomerase activity in the human endometrium throughout the menstrual cycle

In a total of 41 endometrial tissue samples, the relationship betweentelomerase activity and proliferating cell nuclear antigen (PCNA) labellingindex was studied. In samples of endometrium from the proliferative phaseof the menstrual cycle, telomerase activity was found in 15 out of 17 cases(88%). Two samples from the early proliferative phase showed negativetelomerase activity and a low PCNA labelling index. However, three out of16 samples of early secretory phase endometrium showed telomerase activityand a PCNA labelling index. In mid- to late secretory phase endometrium, inmenopausal endometrium and in decidualized endometrium induced byprogesterone neither telomerase activity nor PCNA labelling was found.These results suggest that telomerase activity of the endometrium may becorrelated with the proliferative potential of the epithelial cells andthat its activity may be regulated by oestrogen.