Abstract
Normal rabbits weighing about 2kg was injected with 10mg cortisone acetate (U. S. Merck) suspended in saline per kg body weight, and the change in average number of mitochondria per lymphocyte was followed up to 5 days after injection, using neutral red-Janus green supravital staining. At the same time, blood cell count and histological examination of lymphoid tissues were conducted.
After injection, the mitochondria of lymphocytes of peripheral blood tended to show diminished stainability with less sharp autline. The average number of mitochondria per lymphocyte decreased abruptly 1 hour after injection, showed a minimum value at the 3rd hour, then began to increase gradually and recovered its normal value by the 4th or 5th day (Fig. 1, Table 1). The absolute number of lymphocytes in the peripheral blood, on the other hand, began to decrease from the 3rd hour on, the minimum value being attained at the 24th hour, and thereafter tended to increase slowly but failed to recover its normal value even after 5 days. A marked decrease in the average number of mitochondria per lymphocyte was accompanied by the relative preponderance of mitochondria-poor cells over mitochondria-rich ones (Fig. 2).
In the lymphoid tissues, marked destruction of lymphocytes was observed at the 3rd or 6th hour after injection. At the 12th or 24th hour, atrophy of these tissues was distinct in the cortex as well as in the medulla, and no marked regeneration was observed even after 5 days. The reticulum cells proliferated actively from the 3rd hour on and phagocytized numerous nuclear fragments derived from destructed lymphocytes.
These findings lead to the conclusion that the adrenocortical hormone effects a decrease in the number of mitochondria in circulating lymphocytes, realized for the most part by the decrease of the younger cells which contain more numerous mitochondria than the older forms.
