Regional lymph nodes in the liver of rats in functional pinealectomy.

The effects of functional pinealectomy on the morphological organization of the regional lymph nodes in the liver of rats were studied. Shrinkage of follicles (with increased percentage of germinative centers in them) and reduced count of mature lymphoid cells in the medullary cords indicated more intense migration of B cells from these B-dependent zones. High counts of medium and small lymphocytes in the paracortical zone reflected increasing release of circulating T cells from the blood. Intensification of pinocytosis in dendritic (interdegitating) cells and of fibroblastic reticular cells and activation of protein synthesis in plasma cells indicated activation of immune reactions. Increase in the relative area of lymph node sinuses reflected strained status of their drainage system.