A scanning electron microscopic study of the peritoneal mesothelium covering the genital tract and its ligaments in the cow

This study was undertaken to describe the surface features of the peritonea l mesothelium covering the genital tract and adjacent ligaments of the cow during the oestrous cycle. The relationship between mesothelial surface and spermatozoa was also evaluated after intra-uterine and intraperitoneal ins emination. Surface features of mesothelial cells from 25 cyclic cows were e xamined by scanning electron microscopy acid by image analysis. Presence of spermatozoa was evaluated by scanning electron microscopy in seven additio nal cows. In the external side of the infundibulum, the oviductal mucosa ex ceeds the free mal gin, forming a continuous band measuring 2.5 - 10 mm in width. This oviductal epithelium shows cyclical variations with a predomina nce of ciliated cells during the follicular phase. In respect of the mesoth elium, no clear morphological differences were observed associated with the side of ovarian bursa (internal versus external), or with the phase of the oestrous cycle. Mesothelial cells covering the uterus and mesometrium have a higher microvilli density and length and a smaller cell surface area thi n in the oviduct and adjacent structures. The presence of solitary cilia in the mesosalpinx and mesotubarium superius (infundibulo-cornual ligament) o f some specimens was also observed. When samples were processed without pos tfixation in osmium tetroxide, a layer of amorphous material covered all su rfaces. After intra-uterine insemination of five cows, no spermatozoa were found on their peritoneal mesothelium. Numerous spermatozoa were found afte r intraperitoneal insemination bring attached throughout mesothelial surfac es. These results indicate that there are morphological differences between legions, but no cyclic changes, in the surface features of mesothelial cel ls covering the genital tract and adjacent ligaments of the cow, and that s permatozoa can bind to mesothelial surfaces after intraperitoneal inseminat ion.