MORPHOLOGY OF PLACENTAL SYNCYTIOTROPHOBLAST IN DIFFERENT DATES OF NORMAL PREGNANCY

The placenta is a fetal organ providing the interchange between mother and fetus. An important role in the regulation of local hemostasis belongs to the so-called brush border of syncytiotrophoblast villi, which is directly washed by maternal blood. Microvilli secrete placental alkaline phosphatase, which is a marker of transport processes and activates enzymes for many metabolic processes, participates in cell proliferation and tissue differentiation, carries out IgG transport to the fetus.
The purpose of the work is to characterize the development of syncytiotrophoblast of the epithelium of the placenta villi at different dates of gestation during physiological pregnancy. To achieve the goal of the study, the tasks were set:
1. Study the dynamics of villi branching and the structure of the trophoblastic epithelium of villi from the stage of branched chorion to the end of pregnancy.
2. Determine the area of the trophoblastic epithelium of villi and study the immunohistochemical features of its main components using antibodies placental alkaline phosphatase, β – chorionic gonadotropin. 3. Study the dynamics of structural transformations and secretory activity of cyto- and syncytiotrophoblast at different gestational dates.
Morphogenesis of syncytiotrophoblast of villous epithelium has been studied using histological, immunohistochemical and morphometric studies.
The morphology of microvilli has been traced throughout the gestation period. The first forming microvilli were detected by 5 weeks; by 7 weeks, they were taller and flask-shaped; 8 weeks – had a branching structure; 9 weeks – non-branching structure, large and cylindrical; by the end of pregnancy (39-40 weeks) – rare, and there were no microvilli in the area of syncytio-capillary membranes.
At 4-5 weeks, there is a weak degree of immunoexpression of β-hCG in the invasive cytotrophoblast and cytotrophoblastic epithelium and negative with the antibody against placental alkaline phosphatase. The area of the epithelium is 4,863.2 μm². At 6-7 weeks, the mean area of the villi is 19,705,5 μm². At 8-10 weeks, maximum epithelial area (6,370,7 μm²) and onset of placental alkaline phosphatase immunoexpression in the brush border area. In the period of 18-24 weeks, the area of villi decreases to 3,285,9 μm². At 39-40 weeks, terminal villi dominate with minimal values of the area of the trophoblastic epithelium, which is 786,2 μm². Syncytiocapillary membranes appear. A pronounced two-layer immunoexpression of placental alkaline phosphatase in the epithelium of all types of villi remains.

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