Determination of the vimentin marker in the placenta of cows in normal and delayed afterbirth

Abstract

Modern dairy enterprises suffer financial losses due to the high morbidity of the dairy herd after calving. The current study presents the distribution of the extracellular matrix of the ratio of mesenchymal elements of the placenta in cows during physiological and complicated labor with retained placenta. Caruncle and cotyledon tissues were collected every 6 hours after spontaneous labor until the membranes were released. Depending on the time of release of membranes after birth, the samples were classified as follows: 1 - control group, in which the membranes were released within 6 hours after birth, considered complete, spontaneous and physiological (Partus normalis); 2 - experimental group, in which the membranes were released 9-12 hours after the fetus was delivered, the birth was considered pathological with retention of the placenta (Retenzio sekundarium). Identification of changes in the content of vimentin-containing elements involves the development of a system for express diagnostics of reproductive pathologies in dairy cattle during labor and after calving. Samples of placenta from cows undergoing physiological labor and placenta retention were subjected to standard histological procedures. Paraffin sections of the placenta, 5 µm thick, were mounted on glasses treated with poly-L-lysine (Menzel). Using immunohistochemical and immunofluorescence double staining, the immunolocalization of antibodies to vimentin was studied using clone EPR3776 (rabbit, monoclonal, Taiwan, GeneTex, Int. Corp). The localization of the content of intermediate filaments of the mesenchymal phenotype in the cow placenta was studied, in which the presence of a large number of small capillaries was revealed both in the villi of the cotyledons and in the caruncular crypts during normal pregnancy and childbirth, as well as the equilibrium ratio of mesenchymal structures in the placenta. In childbirth complicated by placenta retention, a decrease in the vascularization of chorionic villi in the cotyledons and degradation of filaments involved in the formation of cellular contacts between the cytotrophoblasts of the chorionic villi of the cotyledons of the fetal part of the placenta and endothelial and epithelial cells of the crypts of the caruncles of the maternal part of the placenta were demonstrated. Pronounced expression of vimentin was found in the cells lining the crypts of caruncles, as well as in the cytoplasmic membrane of villous cytotrophoblasts. A study of the ratio of mesenchymal elements using the immunofluorescent method of double staining of antibodies to vimentin showed that a significant decrease in them both in the cytotrophoblasts of cotyledons and in the epithelial cells of caruncles is observed in the placenta of cows with the development of a state of placental insufficiency, leading to a complication of labor by retention of the placenta. The present study provides the first evidence that vimentin is expressed in bovine placentomes during the gestational, prenatal, and parturient periods and suggests that this filament may, in combination with steriodogenic homones, mediate the separation of the fetal placenta from the maternal placenta.