CHAPTER 1 



LYMPHOCYTES: 



ORIGIN, STRUCTURE, AND 



INTERRELATIONSHIPS 



R. DOROTHY SUNDBERG 



In a previous review (1955) * on lymphocytes and plasma cells, I summar- 

 ized much of the current literature pertaining to the problems of origin, 

 development, interrelationships, and possible functions of these two cell 

 types. Currently my task is similar, but since the interpretation of the results 

 of modern labeling techniques- 6 has suggested that lymphocytes are reutil- 

 ized in the formation of lymphocytes and that circulating blood cells (lym- 

 phocytes of some type or monocytes) 6 are capable of division, I plan to 

 present illustrations that may prove useful in respect to both of these facets of 

 the problem. 



In this regard, the morphologic features characterizing the cells commonly 

 found in the germinal centers will be reconsidered, and the reasons for ack- 

 nowledging somewhat different cell tyes within germinal centers will be 

 re-emphasized. 



LYMPHOCYTOGENESIS 



The origin and development of lymphocytes are difficult to study because 

 lymphatic tissue consists of a variable mixture of reticular connective tissue 

 with its vascular supply and perivascular cells, lymphocytes, plasma cells, his- 

 tiocytes, macrophages, and a few cells that might be classified as monocytes. 

 In normal lymph nodes mitoses may be found in any part of the node, but 

 they are most numerous in the germinal centers of Flemming where one finds 

 macrophages with stainable bodies 7 as well as developing lymphocytes and 

 plasma cells. Considered on the basis of the bulk of lymphatic tissue, mitoses 



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