82 HUMAN ANATOMY. 



and pliable and tough in consistence, in contrast to the bluish opalescent tint and 

 comparative brittleness of the hyaline variety. 



The characteristic feature of the structure of the elastic cartilage is the presence 

 of elastic fibres within the intercellular matrix. The cell-nests are immediately sur- 

 rounded by limited areas of hyaline intercellular substance corresponding to the 

 matrix of hyaline cartilage. The matrix intervening between these homogeneous 

 fields, however, is penetrated by delicate, often intricate, net-works of elastic fibres 

 extending in all directions. The connective-tissue cells lie within the lacunae, in the 

 hyaline areas, and closely resemble the elements of hyaline cartilage. Elastic carti- 

 lage possesses a perichondrium of the usual description. 



Fibrous cartilage, ox Jibro-cartilage (Fig. 112), as the fibrous variety is usu- 

 ally designated, is found in comparatively few localities, the marginal plates and the 

 interarticular disks of certain joints, the symphyses, the intervertebral disks, sesamoid 

 cartilages, and the lining of bony grooves for tendons being its chief representatives. 



Fig. III. 



Cartilage-cells 



i' 



Hyaline areas ^i^A-^* "^ j-^ ^^ ^' L' t.''' lA 



Lacuna contain- 0^> , (' ^^ /;? 'm > ( /i/'^^NV 



ingcell '^^ / £Sf " ^'\ ^ \ 



Elastic net-work 

 of intercellula 

 tissue 





Section of elastic cartilage from the epiglottis. X 450. 



In its physical properties this tissue resembles both fibrous tissue and cartilage, pos- 

 sessing the flexibility and toughness of the former combined with the firmness and 

 elasticity of the latter. A proper perichondriuni is wanting. 



In structure fibro-cartilage closely resembles dense fibrous tissue, since its prin- 

 cipal constituent is the generally parallel wavy bundles of fibrous connective tissue ; 

 among the latter lie small, irregularly disposed oval or circular areas of hyaline 

 matrix which surround the cartilage-cells, singly or in groups. The number of cells 

 and the proportion of fibrous matrix differ in various localities. 



The development of cartilage proceeds from the mcsoblast, the cells of which 

 undergo proliferation and, forming compact groups, become the embryonal cartilage- 

 cells ; at first the latter lie in close apposition, since the matrix is wanting. During 

 the later stages, when the masses of embryonal cartilage map out the subsequent 

 skeletal segments, the cells are separated by a small amount of homogeneous matrix 

 formed through the influence of these elements. 



