TIIK CONNECTIVE TISSUES 



103 



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membrane. The cytoplasm is finely granular, and may contain drop- 

 lets of fat, of glycogen, or of both. Toward the perichondrium the 

 arrangement of the cells in groups is less distinct. Here the cells are 

 fusiform and parallel to the surface. 



The intercellular matrix, when subjected to the usual technic, 

 appears homogeneous. By the use of special methods, such, e.g., as 

 artificial digestion, this ajiparently structureless matrix has been 

 shown to be made up of bundles of fibres, quite similar to those found 

 in fibrous connective tissue. 



Hyaline cartilage forms the articular cartilages of joints, the costal 

 cartilages, and the cartilages of the nose, trachea, and bronchi. In 

 the embryo a young type of 



hyaline cartilage, known as em- 

 bryonal cartilage, forms the 

 matrix in which most of the 

 bones are developed. 



2. Elastic cartilage (Fig. 49) 

 resembles hyaline, but dift'ers 

 from the latter in that its hya- 

 line matrix contains a large 

 number of elastic fibres. These 

 vary in size, many being ex- 

 tremely fine. The elastic fibres 

 branch and run in all directions, 

 forming a dense network of inter- 

 lacing and anastomosing fibres. 



Elastic cartilage occurs in the external ear, the Eustachian tube, 

 the epiglottis, and in some of the laryngeal cartilages. 

 ' 3. Fibrous cartilage (Fig. 50) is composed mainly of fibrillar con- 

 nective tissue. The fibres may have a parallel arrangement, or may 

 run in all directions. Cells are few, and are usually arranged in rows of 

 from two to six, lying in elongated cell spaces between the fibre bundles. 



Fibrous cartilage occurs in the inferior maxillary and sternoclavic- 

 ular articulations, in the symphysis pubis, and in the intervertebral 

 discs. 



Cartilage, ej^cept where it forms articular surfaces, is covered by 

 a membrane, the perichondrium. This is composed of fibrillar con- 

 nective tissue, and blends without distinct demarcation with the 

 superficial layers of the cartilage. 



Like the other connective tissues, cartilage develops from meso- 





L- 



Fig. 49. — Elastic Cartilage from Dog's 

 Ear. X350. (Technic 2, p. 104.) Groups 

 of cartilage cells in fibro-elastic matrix. 



