THE STKTJCTUKE OF THE ELEMENTARY TISSUES. 



43 



1. Inter-articular fibro-cartilage, e. g., the semilunar cartilages of 

 the knee-joint. 



2. Circumferential or marginal, as on the edges of the acetabulum 

 and glenoid cavity. 



3. Connecting, e. g., the inter vertebral fibro-cartilages. 



4. In the sheaths of tendons, and sometimes in their substance. In 

 the latter situation, the nodule of fibro-cartilage is called a sesamoid 

 fibro-cartilage, of which a specimen may be found in the tendon of the 

 tibialis posticus, in the sole of the foot, and usually in the neighboring 

 tendon of the peroneus longus. 



Structure. White fibro-cartilage (Fig. 49), which is much more 

 widely distributed throughout the body than the foregoing kind, is com- 

 posed, like it, of cells and a matrix; the latter, however, being made 









Fro. 



Fro. 50. 



FIG. 49. Transverse section through the intervertebral cartilage of tail of mouse, showing 

 lamellae of fibrous tissue with cartilage cells arranged in rows between them. The cells ar seen in 

 profile, and being flattened, appear staff -shaped. Each cell lies in a capsule. X 350. (Klein and 

 Noble Smith.) 



FIG. 50. White fibro-cartilage from an intervetebral ligament. (Klein and Noble Smith.) 



up almost entirely of fibres closely resembling those of white fibrous 

 tissue. 



In this kind of fibro-cartilage it is not unusual to find a great part of 

 its mass composed almost exclusively of fibres, and deriving the name of 

 cartilage only from the fact that in another portion, continuous with it, 

 cartilage cells may be pretty freely distributed. 



By prolonged boiling, cartilage yields a gelatinous substance called 

 chondrin white fibro-cartilage yields gelatin as well. 



Functions of Cartilage. Cartilage not only represents in the f 03 tus 

 the bones which are to be formed (temporary cartilage), but also offers 

 a firm, but more or less yielding, framework for certain parts in the de- 

 veloped body, possessing at the same time strength and elasticity. It 

 maintains the shape of tubes as in the larynx and trachea. It affords at- 

 tachment to muscles and ligaments; it binds bones together, yet allows a 

 certain degree of movement, as between the vertebrae; it forms a firm 



