New criteria for cytological analysis of sheep vaginal swabs (cytovaginal examination) during sexual hunting, during the sexual cycle, after insemination and depending on the effectiveness of insemination have been developed. Cytological material was collected from the area of the upper vaginal vault using a sterile vaginal mirror, forceps and cotton gauze swab. Staining of brushstrokes was performed according to Gimza-Romanovsky. To improve the method of cytovaginal examination, the division of smear epitheliocytes into groups: functional, destroyed, non-nuclear and cells with nuclear pyknosis is proposed. In turn, among the functional cells it is advisable to distinguish between cells of the deep layers of the epithelium (basal-parabasal), intermediate and surface layer (superficial nuclear). The main types of ratio of particles of different groups and subgroups and their prognostic value in the mating season during sexual hunting are revealed. It was found that during the inhibition stage there is an intensive desquamation of the epithelial level, which was manifested by a 2.5-fold decrease in the number of basal / parabasal epitheliocytes and almost four - destroyed epitheliocytes. And already from the 13th day there is an increase in the cells of the functional level due to the proportion of cells of the deep and intermediate level. On the 18th day, the cellular composition of vaginal smears in sheep acquired characteristics characteristic of the stage of arousal. Thus, compared with the 6-8th day of the cycle, the number of destroyed epitheliocytes (p <0.001) and naked nuclei (up to 8.3 ± 1.6) doubled again (up to 12.0 ± 0.7) against the background of a decrease in 4 times (to the initial level) of cells with pyknosis of the nucleus. The main cytological sign of pregnancy from the fourth day after insemination was a 2.7-fold increase in the number of destroyed cells and "naked" nuclei. In the following days of the study, except for the 13th day, this difference ranged from 1.3 to 4.3 times (8.3 ± 5.4 to 14.7 ± 3.6%), compared with the corresponding figures in unfertilized ewes. Also on the 13th day after the introduction of sperm in fertilized females there is a tendency to increase the number of deep layer cells and the acquisition on the 18th day of a probable difference in the ratio between the number of deep and surface cells - 5: 1. Changes in the distribution of deep and surface cell particles in unfertilized animals indicate the manifestation of the next stage of excitation and the predominance of epithelial cell differentiation. In contrast, in pregnant females, the proliferation of the deep layers of the vaginal epithelium increased.

Key words: ewes, sexual cycle, sexual hunting, vaginal smear, cytological composition, pregnancy.