THE CELLS IX CONNECTIVE TISSUE. 



47 



Lymphocytes (Fig. 49, 1) are a form of blood corpuscle consisting 

 of a round nucleus containing block-like masses of chromatin, and of 

 a narrow rim of protoplasm. Plasma cells (Fig. 49, p) are derived from 

 lymphocytes by an increase in their protoplasm which stains deeply with 

 most stains, but especially with basic dyes such as methylene blue. It 

 is a dense protoplasm which contains no distinct coarse granules. A clear 

 area around a diplosome or a group of centrosome granules may be found 

 in favorable specimens. The resting wandering cells (Fig. 49, r. w.) are 

 said also to be derived from lymphocytes. They resemble connective 

 tissue cells (fibroblasts) but do not produce fibers. Their nuclei are smaller, 

 darker, and more irregular. Their protoplasm, which extends in irregular 

 processes, contains scattered coarse granules staining deeply with basic 

 stains. These cells have been called dasmatocytes . In amphibia there 

 are connective tissue cells with slender 

 processes full of granules. These are 

 described as producing detached frag- 

 ments, and so were named clasmato- 

 cytes. In mammals the fragmentation 

 has not been observed and the "clas- 

 matocytes" are so different from those 

 of amphibia that the term is scarcely 

 applicable. The resting wandering 

 cells or dasmatocytes have been con- 

 sidered varieties of mast cells. The 

 mast cells (Fig. 49, m) are characterized 

 by coarse protoplasmic granules stain- 

 ing intensely with basic stains. These 

 granules are soluble in water and are 

 poorly preserved in ordinary sections. 

 Eosinophiles (Fig. 49, e) also have coarse granules, but they do not stain 

 with basic dyes; they have great affinity for acid stains, particularly cosine. 

 Their nuclei are round or indented. 



The free cells of connective tissue occur especially along the courses 

 of small blood vessels. They will be better understood by the student 

 after examining blood, for they are closely related to the white corpuscles 

 to be described later. All forms of blood corpuscles are to be found at 

 times in the meshes of connective tissue. 



The intercellular spaces of connective tissue are of special importance. 

 Between the fibril bundles, the cells and the elastic network, there remain 

 spaces filled with fluid. They are extensive in reticular, mucous, and 

 loose connective tissue, but are reduced to slender channels in the dense 



FIG. 49. THE CELLS OP LOOSE CONNECTIVE 

 TISSUE, THE LOWEST Row FROM A 

 RABBIT, THE REST FROM A GUINEA PIG. 

 (After Maximow.) 



e., Eosinophile; f., fibroblast; 1., lymphocyte; 

 m., mast cell; p., plasma cell; r. w., resting 

 wandering cell. 



The nuclei are usually round. 



