Endometrial Cytology at Luteal and Follicular Phases of the Ovarian Cycle in Cows

The aim of the study was to examine cytological changes in the uterus in cows during the follicular and luteal phases of the ovarian cycle, as well as to compare two different methods (brush and flushing) used for cytological material collection and to evaluate their usefulness for monitoring of the endometrium. Ovarian cycle phases were confirmed by ultrasound and by the level of sex hormones (17-β-estradiol and progesterone). The following types of cells were identified in the cytological smears: type I - surface cells; type II - intermediate cells; type III - basal cells; polymorphonuclear leukocytes (PMNs); L - lymphocytes. The number of type I and III cells was statistically significantly higher in the follicular phase than in the luteal phase, both in smears prepared using a brush (P<0.001) and by uterine flush (P=0.003). The number of type II cells was statistically significantly higher in the luteal phase than in the follicular phase in both methods (P<0.001). The results of the study show that phases of the ovarian cycle in cows can be identified based on changes in the quality and percentage of different types of endometrial cells in a cytological examination.