ULTRA-STRUCTURAL AND MORPHOMETRIC CHANGES IN ENDOMETRIAL CUPS OF THE UTERUS IN MARES

Abstract

Results are given from studies into ultra-structural peculiarities of chorionic cells depending on a developmental stage of endometrial cups of the uterus in mares. Investigations were carried out at the Research Institute of Veterinary Science of Eastern Siberia, Chita, Transbaikal Territory. Regular, generally biological, structural and functional changes have been observed in the mucous membrane of the genital tract of mares caused by changing phases of sexual cycles and pregnancies as well as by he appearance of temporary specific structures of the uterus in the endometrium that is a specific feature of the horse’s reproductive system. The presence of large chorionic cells has been revealed that are represented by the three types of cells: single-nuclear, dual-nuclear and vacuolating. The maximum number of single-nuclear chorionic cells was recorded during the period of endometrial cups formation (78%), by the period of rejection their number decreased to 48%. The maximum number of dual-nuclear cells of up to 34% was found during the period of their rise. The number of vacuolating cells increased from 4 to 35% by the moment of rejection of these cups. It has been found that single- and dual-nuclear chorionic cells in the early period of endometrial cups development always demonstrate the presence of well-developed granular endoplasmic reticulum with long, narrow profiles and ribosomes densely located on their membranes. The nuclei of chorionic cells havedifferent shapes from oval to round. The nuclear membrane is very rugged, nuclear pores are well expressed. The structure of chromatin in the nucleus is constantly changing; in certain cells, it is located diffusely, in other cells, its individual clumps are concentrated on the inner surface of the nuclear membrane. The nuclei of glandular cells contain significant amounts of chromatin clumps located diffusely throughout the nucleus but in certain glandular cells chromatin clumps are concentrated at the inner layer of the nuclear membrane.