JS The Lymphocyte and Lymphocytic Tissue 



SUMMARY 



The hypothesis of the origin of lymphocytes from a previously phagocytic 

 reticular cell that contains degradation products of phagocytosed lympho- 

 cytes and thus would serve to explain the conservation of labeled DNA and 

 the curiously "long" life span of lymphocytes has been examined and sup- 

 ported by new illustrations from dry film material. 



The intimate union of cytoplasm of the lymphocytes surrounding the 

 phagocytic reticular cells has been compared with a similar union between 

 normoblasts and reticular cells. The latter allows normoblasts to receive fer- 

 ritin from the reticular cells by a process comparable to nursing (Bessis). 36a I 

 suggest that although the reticular cells do eat the lymphocytes, the lympho- 

 cytes probably also get sustenance from the reticular cells. That other peri- 

 reticular cells (plasma cells) may also receive materials essential to their 

 growth or function m this way is equally obvious, and the importance of the 

 perireticular position of plasma cells to their possible function in antibody 

 production deserves further investigation. 



The developmental potentialities of lymphocytes have been mentioned. 



The confusion regarding cell types in the germinal centers has been dis- 

 cussed. The fact that the morphologically immature cells are occasionally 

 present in normal blood and are numerous in the blood in lymphocytic reac- 

 tions has been emphasized by labeling techniques. These cells, known to be 

 capable of mitosis, show incorporation of tritiated thymidine into DNA and 

 can be studied by radioautography. The fact that immature lymphocytes 

 (narrow-bodied cells morphologically intermediate between lymphocyes and 

 small blast forms comparable to the lymphoblasts of acute lymphatic leu- 

 kemia) occur in the lymph nodes, bone marrow, thymus, and, in small 

 numbers, in the blood has been re-emphasized in order that their role as 

 tritium-labeled cells might be clarified. 



ACKNOWLEDGMENTS 



I wish to thank Mr. Henry Morris for the preparation of the photomicrographs. 



I am deeplv grateful to Dr. Lucille J. Hoilund for many of the colored photo- 

 micrographs used in the original presentation of this paper at the Academy course 

 in Boston and for help with the literature and manuscript. I am also indebted to 

 Mr. Gordon Herbst for his help in preparation of the manuscript. 



REFERENCES 



1. Sundberg, R. D. Lymphocytes and plasma cells. Ann. New York Acad. Sc. 



59:671, 1955. ,. . , , , ■ n 



2. Hamilton. L. D. Nucleic acid turnover studies in human leukaemic cells 



and the function of lymphocytes. Nature 178:597, 1956. 



