Med. Weter. 2021, 77 (10), 475-479

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The role of placental immunological, pro-inflammatory, and proteolytic factors in the process of fetal membrane expulsion in mares
The placenta is a temporary organ necessary for prenatal life and the development of eutherian mammals. In the mare it should be expelled within 3 hours of expulsion of the fetus. A delay in its separation can have serious or fatal consequences for mares. The preparation of the mare for the expulsion of the fetal membranes most likely requires immunological interactions between placental antigen and the mare’s immune system. The latest results suggest that fetal membrane retention is related to disorders of inflammatory processes in the placenta, including a lower expression of prostaglandin endoperoxide synthase-2. These disorders in the pro-inflammatory response and disturbances in the activity of the proteolytic enzyme network may lead to adhesion between the fetal and the maternal parts of the placenta. The resulting adhesion may cause the fetal membranes to be thicker and less flexible, making them difficult to expel. Understanding the mechanism of placental retention may contribute to the development of effective methods to prevent and treat this condition.
horse, parturition, fetal membranes, placenta