[Hematopoiesis and changes in the RES of the spleen pulp in fibrosarcoma-bearing rats].

The transplantable fibrosarcoma of the Rat gives birth to different modifications in the splenic structures, and a strong perturbation is found within the enzymatic activities. The macrophages have an altered acid phosphatase activity. This is in marked contrast to the increase in number of the alkaline phosphatase polymorphonuclear cells, which are originated from myeloid areas in the red pulp. Lymphoïd-reticular cells, possessing one 5'nucleotidase activity, seem to be responsible, possibly, by forming numerous clonal systems during the development of this fibrosarcoma. The role of this separate system is discussed.