Lymphocytes: Origin, Structure, and Interrelationships 9 



1-7, 1-8) to the "hematopoietic reticular cells" in the blood in leukemic reti- 

 culoendotheliosis (Figs. 1-9 through 1-12) , it is apparent that Trowell's hy- 

 pothesis 10 ' 20 can be supported by material seen in dry films as well as in sec- 

 tions. I failed to recognize this evidence prior to reading his papers. In 1947 I 

 provided illustrations (Figs. 1 and 2 of Reference 8) of cells which are obvi- 

 ously "histiocytic" to emphasize the fact that the hematopoietic reticular cell 

 in Figure 1-3 had a reticular nucleus, but I did not recognize the significance 

 of my illustrations. 



Fig. 1-9. Blood film from leukemic reticuloendotheliosis. Note 

 the nucleus of reticular cell in center; the cytoplasm of this cell 

 has indistinct peripheral boundaries. (This reticular cell is re- 

 markably similar to the phagocytic reticular cells of the lymph 

 node imprints.) The reticular cell to the left and below it is vir- 

 tually identical with it, but the cytoplasm is hyaline, almost 

 colorless, and distinctly bounded. This is a hematopoietic reticular 

 cell as is the cell to the right of it, but the latter shows a more 

 leptochromatic nuclear pattern and more cytoplasmic basophilia. 

 (x 800) 



Histochemical analyses of the phagocytic cells utilizing desoxyribonuclease 

 and ribonuclease should give some insight into the nature of the cytoplasmic 

 contents of many varying colors, which contents seem to have been confused 

 with the cell's own cytoplasmic constituents. Utilizing ribonuclease, we have 

 removed the basophilic component from cells of the bone marrow, including 

 osteoblasts, 34 - 35 and have demonstrated that subsequent to this procedure, 

 alkaline phosphatase is still present in osteoblasts. Using the Prussian blue 

 reaction as a "counterstain," we have "removed" reticulation from reticulo- 

 cytes and normoblasts and have found that many flocculent blue staining 

 masses and granules contained in macrophages of the marrow and the lymph 

 nodes have disappeared. If countei staining with the Prussian blue reagent is 



