68 



HISTOLOGY 



some, in a clear area of protoplasm, has been found close beside the nu- 

 cleus. In ordinary specimens, stained with haematoxylin and eosin, the 

 centrosome is not seen, and the entire cytoplasm is quite inconspicuous; 



I- b.v. 



FIG. 55. CONNECTIVE TISSUE CELLS (c) AND A MAST CELL (m )FROM THE MESENTERY OF A RAT. X 1000; 

 b.v. a small blood vessel lined with endothelial cells. The specimen was fixed in alcohol and stained with 



Unna's methylene blue. 



but the nuclei stand out prominently along the edges of the fibers (Fig. 

 56, x). 



Cells in connective tissue which differ from the fibroblasts by having 

 abundant protoplasm in the form of large round cell bodies, were named 



Pic. 56. CONNECTIVE TISSUE CELLS (c) A LYMPHOCYTE 0) AND PLASMA CELLS (p) FROM A LACTATING 



HUMAN BREAST. X 1000. 

 A vacuolated plasma cell is shown at v, and a connective tissue cell on edge is seen at x. 



plasma cells by Waldeyer (Arch. f. mikr. Anat., 1875, vol. n, pp. 176- 

 194). He stated that they develop from connective tissue cells, and are 

 always arranged about the blood vessels. Two years later, in the same 



