52 



THE TISSUES. 



FIG. 20. 



branes, as in the capsules surrounding organs and the corium 

 of the skin. These are often fibrous tissue, made up of inter- 

 lacing fibers ; in other cases, especially in the basement-mem- 

 branes which support epithelium, they consist of flattened 

 connective-tissue cells joined edge to edge in a single layer. 



Adipose or fatty tissue (Fig. 20) occurs in large masses 

 under the skin, in the omentum, about the viscera, especially 

 the kidneys and heart, and elsewhere. The cells are large, 



distended spheres of fat, which 

 has been accumulated in the 

 cell-body until the original pro- 

 toplasm has been compressed 

 into a thin atrophied membrane 

 enveloping the fat, and the 

 nucleus has been pushed out into 

 the periphery. The cells are 

 spherical in shape, and are 

 packed together in masses, with 

 inconspicuous fibres between. 

 Fatty tissue merges into areolar 

 tissue in which the connective- 

 tissue cells become filled with 

 fat and crowded together. 



Retiform tissue (Fig. 21) con- 

 sists of a reticulum of fine interlacing fibres, covered, espe- 

 cially at the intersections, with flat stellate endothelioid con- 

 nective-tissue cells. This tissue forms the framework of lym- 

 phoid or adenoid tis&ue, as in lymph-follicles and glands, in 

 which the open spaces of the reticulum are filled with lymph 

 and lymphoid corpuscles, which crow r d the meshes and obscure 

 the network ; these lymphoid corpuscles belong to the class 

 of free cells and are not fixed in the spaces. The framework 

 of the spleen is of a similar character. Retiform tissue may 

 be regarded as an open sustentacular tissue for containing 

 lymph-corpuscles and lymph. The term "retiform" as here 

 used applies only to the connective-tissue framework, and is 

 not taken to include the lymph-corpuscles or as a synonym of 

 lymphoid tissue. 



Cartilage is a specialized form of connective tissue consist- 

 ing of cartilage-cells, which are modified connective-tissue 



Adipose tissue. Crystals of fatty 

 acids are represented in two of 

 the cells. 



