Morphologic characteristics of the thymus in pregnant and newborn mice exposed to sodium arsenite

In experiments with intragastric administration of sodium arsenite to pregnant CBA mice at the dose of 10 and 20 mg/kg during 15 days of gestation (groups 1 and 3), during 15 days before pregnancy and 15 days of gestation (10 mg/kg, group 2) morphological and functional state of the thymus in mothers and newborns was studied. Besides that the content of some trace elements (As, Se, Fe, Mn, Mo, Zn, Cu) in the liver and skin of pregnant mice and total body of newborns was estimated. It was established, that the most pronounced structural changes were seen in the thymus of pregnant mice and newborns of group 2 and 3, which received total dose of sodium arsenite 300 mg/kg ("critical" dose). The changes in the thymus were characterized by accidental involution with a decrease of absolute and relative organ weight, cellularity, especially that of cortical substance, an increase of the apoptotically changed lymphocytes, a decrease of the volume density of cortical layer and increase of the medullar layer and also increase of the thymic bodies number, especially the number of cyst-like structures and epithelial channels. The secondary imbalance of the essential trace elements, first of all that of Fe and Se was observed. This, undoubtedly, plays a significant pathogenetic role in the disturbances of immunological and reproductive systems of the body.