Physiology: A comparative morphological and ultrastructural study of endometrial gland and Fallopian tube epithelia at different stages of the menstrual cycle and the menopause

Cyclical ultrastructural changes in the endometrium and Fallopian tube have been reported previously but in different subjects. The aim of this study is to compare cyclical changes in endometrial gland and tubal (isthmic, mid-tube, ampulla, and fimbria) epithelia in the same subjects with a view to identifying any similarities or differences which may have clinical implications for assisted reproduction treatment. Endometrial and Fallopian tube samples were obtained from women undergoing hysterectomy and salpingectomy. We report similar epithelial surface changes taking place in the endometrial glandular and endosalpingeal epithelia with the exception of the fimbriae. Secretions within endometrial gland lumen and the isthmus increase throughout the late follicular phase and before ovulation, then dissipate in these two regions simultaneously in the early/mid luteal phase. Similarly, in the late follicular and pre-ovulatory phases, the process of granule secretion is similar in the glandular epithelium, isthmus and ampulla. In the fimbriae, no comparable activity is noted during these phases of the menstrual cycle. The differences reflect the functional differentiation between these regions. Equally, the observed similarities highlight the need for further comparative studies to determine the role of these secretions in early embryonic development and their clinical relevance.