Studies on reticuloendothelial system and hemaotpoiesis. I. Studies of extramedullary hematopoiesis.

The author studied the hematopoietic disturbances of rabbit induced by saponin injection and drew the following conclusions: 1) By saponin injection, the structure of bone marrow is disintegrated and hematopoietic cells are released into the circulating blood forming extramedullary hematopietic foci mainly in liver and spleen. The main attacking point of saponin should be RES. Recovery of hematopoietic foci is associated with the recovery of RES. The most marked extramedullary hematopoiesis is found three days after the injection. Thereafter, bone-marrow hematopoiesis proceeds to recovery stage, during which hematopoietic foci in liver and spleen are preserved, especially those in spleen persist fairly for a long time. 2) Daily injections of India ink kept up over a long period of time after the treatment with saponin, prevent the recovery of anemia and bone-marrow hematopoiesis. The lymph nodes, whose RES escaped from the severe damage by India ink, keep the hematopoietic foci for a long time. 3) As far as hematopoiesis is concerned, there seems to be no functional differentiation among RE cells, though they seem to have a special function according to the organs to which they belong, e. g. antibody formation in lymph apparatus, hematopoiesis in bone marrow and red cell destruction in spleen.