[Changes in the cellular elements of the thymus gland in experimental destructive pulmonary tuberculosis].

Lymphoid elements of the thymus were studied by scanning electron microscopy in rabbits susceptible to tuberculosis. The complete Freund adjuvant causes in the thymus a 3-fold decrease in the number of cells with the properties of T-lymphocytes, and an appearance of a new type of cell elements (polygonal shape, with cytoplasmic outgrowths). Formation of a focus of tuberculosis and the development of destructive changes in the lungs occur under conditions of a progressive decrease in the number of T- and B-lymphocytes in the thymus. Delimitation of the pathological process in the lung is characterized by an increase in the number of T- and B-lymphocytes and considerable predominance of polygonally shaped cells with cytoplasmic outgrowths of different lengths and their subsequent replacement by a cell form transitory between T- and B-lymphocytes. A relatively favourable course of the process in the lungs is observed when the cell elements in the thymus differentiate towards B-lymphocytes.