Cytological structure of a vaginal stroke in American mink during estrus

Abstract

The article presents the data of domestic and foreign authors on the features of the oestrous process of American minks. The results of studies of the cytological structure of the vaginal smear in American minks during estrus are presented. The study was conducted on clinically healthy American mink females of the Standard dark brown (+/+) genotype in 92 animals before the technological rut (February 20-28). A vaginal smear was taken at different periods of changes in the external genital organs - the genital loop, taking into account the scoring of its development (from 0 to 5 points). Microscopic examination of smears taken during this period showed a predominance of superficial, intermediate, and parabasal cells and a small number of basal and spindle cells. The analysis of the nuclear-cytoplasmic ratio made it possible to indicate the specificity of the morphometric parameters of the cells of the vaginal integumentary epithelium. Surface epitheliocytes and intermediate cells have a sizeable cytoplasmic area and a low nuclear-cytoplasmic ratio of 0.034. Parabasal cells have the minimum size of the nucleus and cytoplasm but a high value of the nuclear-cytoplasmic percentage, seven times higher than that of superficial cells and three times intermediate. Quantitative proportions of epithelial cells of the vaginal smear cytogram from February 20 to 28 correspond to the proestrus-estrus stage. The data obtained indicate significant features of the morphological changes in the integumentary epithelium of the vagina and the difference in the cytological dynamics of the oestrous cycle in American minks from other mammals. The cytogram of the vaginal smear of minks with a 4-5 point assessment of the readiness of females for mating does not contain the predominant number of keratinized epithelial cells, which is characteristic of most mammals during the period of ovulation. An important morphological criterion in the analysis of the vaginal smear cytogram in minks is the value of the ratio of superficial and parabasal cells and scales and parabasal cells.