EN
The aim of this work was to evaluate the structural changes senn in the endometrial biopsy of mares. Mares were selected for the examination in which the clinical disease or infertility were diagnosed. The research was done on 107 mares, of various race and age. The biopsy specimens were fixed in 10% formalin, paraffin embedded, and routinely stained with hematoxylin and eosin. Some specimens were histochemically stained with Alcian blue and periodic acid Schiff, likewise immunoperoxidase methods were used for the visualization estrogen (ER) and progesterone (PR) receptors. The results of investigation included the following number of cases of specific diseases that were diagnosed: 19 - catarrhal inflammation; 3 - purulent inflammation; 24 - lymphocytic inflammation; 9 - eosinophilic inflammation, 40 - endometriosis; and 1 case of endometrial atrophy. In 11 cases no lesions were found. The endometrial biopsy is a recommended laboratory method for the exact diagnosis of mares’ uterus health status.