The concept of miscarriage includes pregnancy loss from conception to the 20th-22nd week of intrauterine development. Most often, we can observe an early miscarriage of pregnancy – the one, which happened before the 12th week of fetal development, and the incidence of miscarriage from the 12th to the 24th week takes only <4% of the total number of cases. About 50% of all causes of earlyrecurrent miscarriage are chromosomal abnormalities, and in about 40% of cases, the causes are not established (idiopathic recurrent pregnancy miscarriage). In the available literature, we failed to find researches on carbohydrate determinants of the structural components of chorionic villi of human embryos at the period of early pregnancy and comprehensive studies using general histological techniques, lectinohistochemistry, immunohistochemistry and scanning electron microscopy of chorionic villi during the above-mentioned pathology. The aim of the study was to investigate the morphofunctional, immunohistochemical features and role of carbohydrate determinants of chorionic villi of human embryos, died out as a result of sporadic and recurrent pregnancy miscarriage using general histological, scanning electron microscopy, immuno- and lectinohistochemical methods of investigation. For the first time, a complex study with general histological, lectino- and immunohistochemical methods of chorionic villi of human embryos was conducted for sporadic and recurrent pregnancy miscarriage, and a comparative analysis of the results with normal of chorionic villi of human embryos was performed. The first comparative three-dimensional ultramicroscopic study using scanning electron microscopy showed a decrease in the number of syncytial knots and inferiority of the microvilli of syncytial layer of chorionic villi during recurrent pregnancy miscarriage. These events were less pronounced in the villi of the group of sporadic miscarriages and virtually absent in the control group. The highest expression of lectins WGA (DGlcNAc> NeuNAc), GNA (αDMan) was detected in the studied group of recurrent pregnancy miscarriage, namely, in the syncytial layer, cytotrophoblast, and mesenchymal fibers. With CNFA lectin, the microvilli of syncytium, its cytoplasm, cytotofoblast cells, mesenchymal fibers, and Hofbauer cells were well visualized. In the chorionic villi of recurrent miscarriage group, the aforementioned components after marking with CNFA were less mature and integral, there was an inferior microvilli. STA showed similar affinity and binding activity. After conducting a complex immunohistochemical study, there was a decrease in Ki67 expression activity in cytotrophoblast cell nuclei in sporadic and recurrent miscarriages. There also was a change in expression activity, and modification of the distribution of VEGF and Caspase 3 in the structural components of the studied and control samples, and for the first time it was stated about the importance of the distribution of these markers for the sporadic and recurrent pregnancy miscarriage, not just the level of their expression. The PAS reaction, the reaction of alcian and toluidine blue, lectins WGA, GNA, PFA, CNFA, STA, and monoclonal antibodies to Ki67, VEGF and Caspase 3 can be recommended as histochemical markers to predict the possible course of further pregnancies in women with a risk of development of recurrent miscarriage of pregnancy and for the further study of pathophysiological and pathanatomic mechanisms of the development of sporadic and recurrent miscarriage of pregnancy. Key words: pregnancy, chorionic villi, sporadic miscarriage, recurrent miscarriage, lectinohistochemistry, immunohistochemistry, scanning electron microscopy. Branch - Medicine.
