Electro)) Microscopy of the Lymphocyte 59 



with the outfoldings of cytoplasm that characterize many lymphocytes pre- 

 pared by this technique. 



Compound vacuoles are a notable feature of lymphocytic ultrastructure 

 (Figs. 4-5, 4-6) , although occurring in other blood cell types (Reference 1 1, 

 p. 117), notably blood monocytes, and in the rat spleen. 19 They consist 

 essentially of a variable number of small vacuoles contained in a larger 

 one. Outside of the larger vacuole, there are frequently clusters of smaller 

 ones which are indistinguishable from the small ones inside. The vacuoles 

 in the complex are structurally separate. The number of small vacuoles 



Fig. 4-7. Detail of lymphocyte; normal human blood. The Golgi zone (G) consists 

 of flattened sacs, smaller rounded profiles, and a few large vacuoles. Within the 

 concavity of the Golgi zone is the relatively lucid and nearly structureless centro- 

 sphere (cs). In the center of the latter is a centriole (cl), here cut in cross section. 

 The 2 components of the nuclear membrane (nm) are closely approximated in some 

 areas and more widely separated in others, (x 41,000) 



within the parent vacuole in a single section vary from only one or two to a 

 conglomerate so densely packed that recognition of the complex as a com- 

 pound vacuole may be difficult. 



The "small particulate component" of Palade 20 is readily recognizable in 

 blood lymphocytes (Figs. 4-4, 4-5, 4-6) , but the granules do not show an 

 affinity for the endoplasmic reticulum. This situation is characteristic for 

 all of the blood cells except plasma cells (Reference 11, pp. 112, 322) . 



The Golgi zone, centrosphere, and centrioles are so intimately related in 

 lymphocytes that they merit description together. The established concept 

 of light microscopy for large lymphocytes 17 is that two centrioles are sur- 

 rounded by a cytocentrum which in turn is surrounded by the Golgi zone. 



