Features of placenta morphology in herd mares during abortions associated with placentitis

K. R. Nifontov¹ , V. S. Avdeenko², V. I. Fedorov¹

¹ Arctic State Agrotechnological University, Yakutsk, Russia

² Saint Petersburg State University of Veterinary Medicine, Saint Petersburg, Russia

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Volume 26 No. 7

Date of paper submission: 16.02.2026, date of review: 10.04.2026, date of acceptance: 06.05.2026. 

Published: 07/31/2026

Abstract. The purpose of the study was to conduct a detailed anatomical and histochemical study of the placenta of mares kept in herds of Yakutia during abortions associated with placentitis. Methods. Placenta samples (1 × 1 cm in size) from 5 six- and seven-year-old mares were analyzed immediately after the abortion. Samples were taken from 2 mares with normal placental structure and from 3 mares with signs of placentitis after abortion). Placenta samples (5 mm thick, up to 3 cm2 in area) were fixed in a 10 % “HistoSafe” formalin solution. Next, dehydration was carried out in “Isoprep” with a gradual increase in concentration and pouring into “Histomix” paraffin. The IBM SPSS Statistics 26 and Microsoft Excel programs were used for statistical data processing. Results. Morphological changes in the structure of the placenta were revealed in mares after abortion in the fetal membranes. The destruction of the epithelium of the amnion with the formation of vacuoles was observed. Cytotrophoblast cells had a diverse shape (cubic, rounded-oval, flattened, polygonal) and a different volume of cytoplasm, often containing small vacuoles. The cell nuclei were small. A plate of reticular connective tissue was located under the cytotrophoblast. Significant formation of intracellular vacuoles was noted in fibroblastic cells, which made the cells look like rings. Polymorphic infiltration of the connective tissue of the villi and stroma of the microcotyledons, as well as pronounced fullness (hyperemia) of the villi capillaries, was found in the chorioallantosis. Vacuolar fibroblast dystrophy was observed in sections of vascular-allantoic membranes, which manifested itself in the formation of vacuoles and cell shape changes. Mares with placentitis have a strong allantochorial fibrous structure and significantly more connective tissue in the allantochorial villi than in mares with a physiological course of pregnancy and childbirth. Scientific novelty. For the first time, placental topography and the microscopic structure of its cellular components have been analyzed in detail for herd mares. The study is also aimed at identifying specific biomarkers indicating placentitis and determining its predictive indicators.

Keywords: placentitis, topology and histomorphometry, abortion, analysis of cellular placental structures

Acknowledgements. The research was carried out at the expense of the regional grant of the Russian Science Foundation No. 25-16-20118.

For citation: Nifontov K. R., Avdeenko V. S., Fedorov V. I. Features of placenta morphology in herd mares during abortions associated with placentitis. Agrarian Bulletin of the Urals. 2026; 26 (07): 1274‒1283. https://doi.org/10.32417/1997-4868-2026-26-07-1274-1283 (In Russ.) 

  

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