STRUCTURE OF THE VERTEBRATES 



101 



ess in a cut or wound depends upon other connective tissues re- 

 verting to the embryonic condition, filling the opening, and then 

 re-developing into the original type. 



2. Reticular connective tissue fills every available space in 

 the body. A section of a gland or muscle stained for connective 

 tissue will demonstrate this. In either a gland or muscle the 

 reticular fibers surround every cell, interlacing to form a firm 

 network throughout the structure. These fibers are usually con- 

 tinuous with the following, thus binding the tissues and organs 

 strongly together. 



3. White fibrous tissues form the loose areolar tissues found 

 under the skin and most of the tendons and ligaments of the 

 body. The fibers of the latter lie parallel, are strong and tough, 

 and allow of little stretching. 



Reticular 



White fibrous 



Fig. 42. True Connective Tissues. 



Yellow elastic 



4. Yellow Elastic fibers are less abundant than the preced- 

 ing, and are usually mixed with other types. The fibers split and 

 fuse again, and are elastic in nature. They are found in the 

 walls of arteries, in the connective tissues under the skin, and in 

 other places where they automatically pull a structure back 

 into shape after displacement. Most mammals have a strong 

 bundle of these fibers in the dorsal part of the neck. 



5. Cartilage is a strong, firm connective tissue. The cells of 

 cartilage are essentially like those of the true connective tissues, 

 but instead of developing fibers as do the others, they secrete 

 a non-cellular, translucent substance around themselves. As 

 more of this substance is formed the cells are pushed farther 

 apart until the cells lie isolated from each other in the surround- 

 ing matrix. 



The above description applies to the basic structure of all 

 cartilage, and to the adult condition found in hyaline (clear) 



