[Lymphoid tissue of mice spleen in the delayed periods following a single gamma-irradiation].

Morphofunctional state and recombination of cell composition of the spleen structural components were studied in mice Balb/c at delayed (post-irradiation days 21, 30, and 58) periods following a single gamma-irradiation by 6.9 Gy. At none of these time points did the lymphoid structural components of the spleen complete their morphological and cytological recovery. Morphological disturbances included poor development of germinative centers and marginal zones in lymphadens and periarterial lymphoid heads (PALH). Recovery of lymphoid cell population did not go on same pattern. Thus, by day 58 of recovery, in PALH small lymphocytes regained basal level but rose concentration to 79% in the lymphadens without germinative centers and to 60% in the lymphoden mantle and red pulp. Elevation of mitotic and cell differentiation activities was not equal. Destructive processes approached normal values in PALH and red pulp and remained by 85% beyond basal values in lymphodens. Mature/immature plasmatic cells ratio was modified. Moreover, plasmocytes (mature cells) that are responsible for humoral immunity, localized in unordinary sites, i.e. in PALH and lymphodens without germinative centers. Adaptive changes observed in the red pulp at delayed time-points after irradiation were manifested by development of myelopoiesis focuses with high concentrations of young forms of neutrophils and megakaryocytes.