Morphology and Ploidy of Smooth Muscle Cells in Chorionic Arteries under Different Hemodynamic Conditions.

Smooth muscle cells from the arterial wall of placental chorion were studied at 39-40-week gestation. The content of mono- and binuclear tetraploid myocytes was higher in sites of arterial branching and turns (27.3% vs.

Structural Organization of Arterial Vessels in Placental Hypoplasia.

Structure of the placental arterial bed was studied using histological and morphometric methods. The formation of smooth muscle regulatory complexes in blood vessels of the chorionic plate and chorionic villi was demonstrated. These complexes are genetically determined and represent a variant of compensatory and adaptive reorganization of the placental arteries for adequate fetoplacental blood supply under normal conditions and placental underdevelopment.

The use of micronucleus test for detection of genotoxic damage to the thyroid gland.

We studied the possibility of using the micronucleus test in in vivo experiments on the model of rat follicular thyrocytes prestimulated to cell division (hemithyroidectomy). Single administration of N-nitroso-N-methylurea produced a significant dose-dependent effect on micronucleus formation in thyrocytes and polychromatophilic erythrocytes of the bone marrow. The test system allowed us to reveal a cumulative effect of 2-fold and 4-fold treatment with the mitogen in low or subthreshold doses on the thyroid gland.

Ploidy of micronucleated thyrocytes induced by methylnitrosourea injection.

Ploidy of thyroid parenchyma was studied in adult rats in the control and on day 9 after hemithyroidectomy; operated animals received 3 injections of N-nitroso-N-methylurea. The population of follicular thyrocytes is mainly diploid; total count of polyploid cells increased from 4.4% in the control to 8.