232 



PLASMA-CELLS. 



minute granules scattered through it ; they have a large oval nucleus with a fine 

 intra-nuclear network and nucleoli. 



In many membranous forms of connective tissue, the flattened cells form an 

 epithelial-like covering to the surfaces of the membrane or membranes (fig. 270), and 

 may even complete the latter by bridging over any gaps existing between the 

 bundles of fibres forming the membrane. Such epithelioid tracts may be of 

 considerable extent. It is often observable, that the cells at the margin of the 

 patch have processes at their free border, which are connected with the ordinary 

 scattered cells of the tissue (see fig. 269). 



Granular cells. Besides these flattened cells with fine granules, other cor- 

 puscles are met with in the connective tissue, which are more decidedly granular 

 (fig. 262, #), having actual distinct, somewhat coarse, granules in their protoplasm. 

 Although they were classed along with the vacuolated cells, next to be described, by 



Fig. 270. EPITUELIOID CELLS OF CONNECTIVE TISSUE. FROM THE SURFACE OF AN APONEUROSIS 



TREATED WITH NITRATE OF SILVER. IIlGHLY MAGNIFIED. (E. A. S.) 



Waldeyer, under the name of plasma-cells, they are perfectly distinct elements, and 

 it will be better therefore to reserve the name " plasma-cells " for the vacuolated 

 corpuscles, and to employ the name of granular cells for these, which are filled with 

 obvious granules. The granular cells are especially abundant near the blood-vessels, 

 and they also occur in large number in areolar tissue in which fat is to be deposited. 

 The granules are of an albuminous nature ; they stain deeply with eosin 1 and with 

 many aniline dyes. These cells vary much in size and shape ; many are spheroidal, 

 but they may be branched or even flattened. Their nuclei are round or oval. 



The plasma-cells (fig. 262, p. p.) are distinguished from the lamellar and granular 

 cells by the extreme vacuolation of their cell-substance. The protoplasm between the 

 vacuoles is clear, but may contain a few fine dark granules. The fluid which occupies 

 the vacuoles is presumably of the nature of lymph or blood-plasma : it is less 

 refracting than the substance of the protoplasm. It is not contained in the meshes 

 of a spongioplasmic network but is in distinct vacuoles. These plasma-cells are 

 frequently elongated and they may have short branching processes but they are seldom 



1 Hence termed " eosinophile cells " by some authors. The same term has also been applied by 

 Ehrlich to those leucocytes which have obvious granules, staining with eosin (see p. 213). 



