Examination by scanning electron microscopy of oviductal epithelium of the prolific Chinese Meishan pig at follicular and luteal phases.

The luminal surfaces of epithelial cells in the fimbriae, ampulla, isthmus, and utero-tubal junction of the oviducts of the prolific Chinese Meishan pig at follicular and luteal phases of the estrous cycle were examined by scanning electron microscopy. Marked cyclic changes were observed on the surfaces of cells in the fimbriae and ampulla, but little change was found in the isthmus and at the utero-tubal junction. The cells of the fimbrial epithelium in the follicular phase were densely ciliated, and the cilia partially concealed the bulbous processes of the secretory cells. In the luteal phase, the secretory cells predominated in the epithelium, and most of the ciliated cells were hidden by the processes of the secretory cells. The ampullar epithelium showed similar changes, but to a lesser extent. In the isthmus and at the utero-tubal junction, the secretory cells had many microvilli on their bulbous processes at the follicular phase, but they were flat and the microvilli were fewer in number and shorter in length during the luteal phase. Conspicuous solitary cilia protruded from the surfaces of secretory cells in the fimbriae and ampulla during the luteal phase. These results demonstrate that there are regional variations in the cyclic changes associated with the oviductal epithelial cells of the Chinese Meishan pig.