Anatomical and histological alternations of the spleen in rat, Rattus norvegicus exposed to mercury

This study aimed to investigate the histological, morphological and histochemical structures of the spleen of rats exposed to mercury chloride. Sixteen adult rats, Rattus norvegicus were obtained and divided into two groups as a control group that orally administered distilled water daily for ten weeks, and the second group administrated Hgcl2 at a dose of 3mg\kg B.W\IP three times weekly. The results showed a significant difference as a decrease in the weight of the spleen of treated rats and an increase in the mean length of the spleen. There were significant differences in capsule thickness and the diameter of lymphoid follicles of the spleen compared with the control group. The mean capsule thickness significantly decreased, while the diameter of lymphoid follicles was increased. The histological examinations revealed lymphoid hyperplasia and proliferation of the red pulp (PALS) macrophage with vacuolated sub capsular cells, haemosidrosis with fibrous tissue, and aggregation of inflammatory cells with giant cells, aggregation of necrotic foci and minerals in granuloma center. In addition, in the PAS staining, alternation and necrosis of splenic cord, accumulations of hemosiderin in the red pulp, cellular degeneration and necrosis with an accumulation of adipose tissue, and degeneration of lymphocytes in the cortical area of the splenic corpuscle were observed. The Mallory trichrome staining revealed necrosis and degeneration of endothelial cells with loss of nuclei, degenerations of germinal center and necrosis of medullary sinuses in addition to hemosiderin accumulations.