Scanning and transmission electron microscopic study of the obiductal epithelium of female albino rat during follicular and luteal phases of the estrous cycle

This work was done on fifteen virgin adult female albino rats to study regional differences and cyclic changes of the oviduct epithelium during the follicular and luteat phases of estrous cycle. Specimens from the fimbriae, ampulla and isthmus of the oviducts were prepared and examined by scanning and transmission electron microscopy. Scanning electron microscopic examination revealed that during the follicular phase, the fimbrial and ampullary epithelium were heavily ciliated. The cilia were uniform in length with even distribution and they concealed to a great extent the secretary. However, during the luteal phase the secretary cells were predominant with characteristic microvilli and solitary cilia protruding from their surfaces. The isthmic epithelium showed few changes between the follicular and the luteal phases of the estrous cycle, where the ciliated cells were irregularly distributed at both phases. However, the secretary cells appeared more prominent during the luteal phase. Transmission electron microscopic examination showed that the secretary cells of the fimbriae were columnar with ovoid nuclei and numerous long free border microvilli; the ampullary secretary cells were broad with few irregular microvilli. However, the isthmic secretary cells were broad with short blunt microvilli. Solitary cilia were found among the microvilli of the fimbrial and ampullary secretary cells. Two types of secretary granules were observed in the oviduct secretary cells, electron dense and electron lucent. During the follicular phase the secretary granules were almost of the electron dense type. However during the luteal phase, they increased and exhibited an electron - lucent appearance with centrally or peripherally located electron dense dots or patches. It is obvious from this study that the findings obtained be SEM were in accordance with and confirmed what found by the TEM. Both revealed marked regional differences and cyclic changes in the oviduct epithelium which might be necessary to meet varied requirements of the developing ovum. So, the tubal cells have to adjust themselves structurally and biochemically for such purpose