Factors influencing the infiltration of eosinophils into the mare’s endometrium

Abstract

Factors and consequences related to infiltration of the endometrium by eosinophils in the mare are not fully understood. The aim of the study was to determine the frequency of eosinophilic infiltration into the endometrium in chronically infertile mares and to determine factors conducive to this type of changes. A total of 117 samples of endometrium were collected from infertile mares, 15 samples of endometrium were collected from maiden mares, and all were evaluated histologically. Eosinophilic infiltration of the endometrium was found in 59 mares; in 10 mares, eosinophiles were the predominant cells that had infiltrated the endometrium. The probability of eosinophilic infiltration of the endometrium increases with the age of the mare and with a higher score of endometrial degeneration. The simultaneous infiltration of the endometrium by polymorphonuclear cells and mononuclear cells, in mares being in oestrus, and in mares having fluid in the uterus, also increased the probability. In the group of young mares, eosinophilic infiltration of the endometrium was not detected. Eosinophilic infiltration of the endometrium increases in chronically infertile mares with age and with the presence of other abnormalities observed in the endometrium. We suspect that presence of eosinophils in endometrial tissue together with other abnormalities can be considered as reducing factor for future fertility, however, this hypothesis should be evaluated critically.