[Structural and functional organisation of the spleen lymphoid tissue after exposure to hypergravitation]

Using the stereologic methods and quantitative analysis of the cells of lymphoid series in the splenic white pulp of Wistar rats, the changes were studied after continuous 5-day-long exposure to hypergravitation of 2 G. The injurious effect of hypergravitation was manifested in the reduction of the dimensions of periarterial lymphoid sheaths (PALS) and of lymphoid nodules, marginal zone dilatation and the disappearance of lymphoid nodules with germinal centers. Changes in the cell population of the white pulp are indicative of the suppression of blast-transformation and cell reproductive activity (as demonstrated by the disappearance of blast cells and the mitotic cells) and the reduction of lymphocytopoiesis in the organ lymphoid tissue. The proportion of immature plasma cells is increased. The changes demonstrated are more pronounced in PALS than in lymphoid nodules. The significant cellular reorganization of the marginal zones is the reflection of compensatory processes, which develop in response to the injurious effect of hypergravitation on the lymphoid tissue of the spleen.