Abstract
Morphological changes in the epithelium and smear from the vaginal vestibulum of cows were examined histologically at different stages of the estrous cycle and at 5 months of pregnancy using light and scanning electron microscopes.
A stratified cubic epithelium was observed during the estrous cycle and a stratified squamous epithelium during pregnancy. The epithelium was thickest at estrus and thinnest at pregnancy. Dur-ing the estrous cycle and gestation period many leucocytes were observed in the epithelium. Thenumber of leucocytes was greatest at estrous stages and their nuclei were elongated in the intercel-lular spaces.
In vaginal smears, the number of epithelial cells and leucocytes was the greatest at the estrous stages and decreased at diestrus, followed by a slight increase at around 13 days after estrus. All of the leucocytes were identified as neutrophils. The shape of the nuclei became string- and spindle-like in appearance. These nuclei migrated and gathered to form rope-like structures. Leucocytes ap-peared with epithelial cells in smears. The deformed nuclei appeared with neutrophils and when nuclear deformation of leucocytes occurred, there was a decrease in leucocyte number in the lumen of the vaginal vestibulum.
