42 ELEMENTS OF HISTOLOGY. [Chap, v. 



They always contain coarse granules, which are com- 

 posed of a substance which is not fat, but something 

 between protoplasm and fat. They stain deeply in 

 dyes, and the corpuscles correspond to similar "gra- 

 nular" corpuscles of the blood. These "granules" 

 may change into fat globules, and thus the plasma 

 cell becomes transformed into a fat cell. 



48. The wandering cells occur almost in all loose 

 fibrous tissues, chiefly around or near blood-vessels ; 

 they are not numerously met with in the healthy 

 state, but increase greatly in the state of inflamma- 

 tion of the part. The larger kinds are met with 

 in certain localities only ; in the sub-lingual gland 

 of the dog and guinea-pig they occur in numbers 

 between the gland tubes or acini. They are also 

 found in the mucous membrane of the intestine. 

 The plasma cells are met with chiefly in the inter- 

 muscular tissue, in the mucous and sub-mucous tissue 

 of the intestine, in the trabeculse of the lymphatic 

 glands, and in the omentum. 



49. Development of fibrous tissue. Fibrous 

 connective tissue is developed from embryonic connec- 

 tive tissue cells, i. e., from spindle-shaped or branched 

 nucleated protoplasmic cells of the mesoblast. The 

 former are met with isolated or in bundles, as in the 

 umbilical cord or embryonic tendon. The latter 

 form a network, as in the foetal skin and mucous 

 membrane. In both instances the protoplasm of the 

 embryonic connective tissue cells becomes gradually 

 transformed into a bundle of elementary fibrils, 

 with a granular-looking interstitial substance. The 

 nucleus of the original cell finally disappears. A 

 second mode of the formation of fibrous connective 

 tissue is this : the embryonic connective tissue cell, 

 while growing in substance, produces the fibrous tissue 

 at the expense of its peripheral part. A remnant of 

 the protoplasm persists around the nucleus. 



