UDC

611.664[599.323.4+591.16]

Authors

Ol’ga V. Dolgikh*, Yuriy V. Agafonov*, Andrey L. Zashikhin*, Marina V. Men’shikova*
*Northern State Medical University (Arkhangelsk, Russian Federation)
Corresponding author: Ol’ga Dolgikh, address: prosp. Troitskiy 51, Arkhangelsk, 163000, Russian Federation; e-mail: olvado@mail.ru

Abstract

For gestation and parturition to take a normal course, there should be close cooperation between the uterus regions with different contractile activity which is determined by the structural and functional organization of myometrial smooth muscle tissue (SMT). The purpose of this study was to conduct a comparative morphometric and cytophotometric analysis of SMT in placental and interplacental myometrial regions of rat uterine horns at different stages of gestation. Morphometric parameters of isolated smooth muscle cells (SMCs), DNA content in the nuclei, and total cytoplasmic protein were determined. In the composition of SMT, subpopulations of small, medium-sized and large myocytes were identified, differing in their morphometric and metabolic characteristics. The research revealed that the dynamics of the structural and functional organization of SMT in placental and interplacental regions was unidirectional until mid-gestation. In the first week of gestation, the number of small cells with the greatest proliferative potential increased significantly compared to other subpopulations of SMCs. In the second week, the population was mostly comprised of medium-sized myocytes; proliferative activity decreased and the share of SMCs with high levels of cytoplasmic proteins increased. At the end of gestation period, the structure of SMT in interplacental regions differed significantly from that of placental regions. Medium-sized SMCs prevailed in the population, while the share of large myocytes was half and that of small cells thrice as large as in placental regions. Such prevalence of small and medium-sized SMCs in interplacental regions increases the potential of the myometrium for subsequent post-natal transformation.

Keywords

interplacental region, myometrium, smooth myocyte, uterine smooth muscle tissue

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