FURTHER STUDIES OF A LYMPHOCYTIC HEMOGRAM AND ITS RELATION TO LYMPHOCYTOPOIESIS : Ⅱ. VARIATIONS IN MITOCHONDARIAL CONTENT IN BLOOD LYMOHOCYTES IN RELATION TO THE PROCESSES OF REGENERATION OF THE LYMPHATIC

1. In a series of young sbult albino rats weighing around 200g, variations in mitochondrial number in blood lymohicytes were observed in relation to the processes of regeneration of the lymphatic tissue , the Flemming's secondary nodules in particular, after total body X-irradiationin a dose of 600 r. 2. Immediately after irradiation, there occurred a sharp drop of both the lymphocyte count and the average number of mitochondria per lymphocyte in the blood. The mesenteric lymph nodes and splenic white pulp were severely depleted of lymphocytes through a massive destruction of these cells. The Flemming's secondary nodules had disappeared within several day. 3.During the regenerative processes of the lymphatic tissue, an extensive new formation of Flemming's secondary nodules in the mesenteric lymph nodes and spleen was observed almost coincident with a remarkable transient elewation of the average number of mitochondria in blood lymphocytes, during the period between the 14th and 21st days after irradiation. 4.These findings provide a strong evidence to support the view that a marked rise in mitochondrial number of blood lymphocytes takes place as a consequence of extensive new formation of Flemming's secondary nodules in the lymphoid organs, which, in turn, indicates an increase in production and delivery of lymphocytes to the blood.