Histological Changes in the Epithelium of Thai Swamp Buffalo Oviduct at Follicular and Luteal Phases

The samples from the infundibulum, ampulla, isthmus and uterotubal junction (UTJ) of the Thai swamp buffalo oviduct were taken immediately after slaughter at the local abattoir. The histological changes of the epithelium including general characteristics, intensity of periodic acid-Schiff (PAS) staining, cell height and immune cell distribution were investigated by light microscopy. The degree of the histological and morphometric changes was shown to be high in the ampulla and infundibulum compared with that of the isthmus and UTJ at both follicular and luteal phases of the estrous cycle. In the infundibulum and ampulla, cytoplasmic protrusions of the epithelial cells with extruded nuclei were prominent at the luteal phase and disappeared during the follicular phase. However, a strong intensity of PAS reaction was obviously shown in the epithelium of isthmus and UTJ during the follicular phase. The epithelial cell height significantly decreased in the infundibulum and ampulla from the follicular to luteal phases, but not in other regions. The number of intraepithelial leukocytes was significantly different between the stages of the estrous cycle and highest in the infundibulum at the luteal phase. In conclusion, histological observations of Thai swamp oviductal epithelium revealed marked cyclic changes in cellular differences associated with functions of segmental variations.