FIBRO-CARTILAGE. 55, 



Elastic or yellow fibro-cartilage occurs in only a few situations. 

 These are, the cartilage of the external ear and that of the Eustachian 

 tube, and the epiglottis and cartilages of Santorini of the larynx. The 



FIG. 62. SECTION OF RIB-CARTILAGE, SHOWING CELLS AND CELL-GROUPS IN A 



SOMEWHAT FIBROUS-LOOKING MATRIX. 



Two or three empty cell-spaces are seen from which the cells have dropped out in preparing 



the section. 



matrix is everywhere pervaded with well-defined branching fibres, 

 which unite with one another to form a close network (fig. 63). These 

 fibres resist the action of acetic acid, and are stained deeply by magenta ; 

 they are evidently elastic fibres. In the ox they are very large, but 

 smaller in man, especially in the cartilage of the epiglottis (fig. 64). 

 They appear to be developed, as with elastic tissue elsewhere (see p. 49), 

 by the deposition of granules of elastin in the matrix, which at first lie 

 singly, but afterwards become joined to form the fibres. 



White fibro-cartilage is found wherever great strength combined 

 with a certain amount of rigidity is required : thus we frequently find 

 fibro-cartilage joining bones together, as in the case of the intervertebral 

 disks and other symphyses. Fibro-cartilage is frequently employed to 

 line grooves in which tendons run, and it may also be found in the 

 tendons themselves. It is also employed to deepen cup-shaped articular 

 surfaces ; and in the case of the interarticular cartilages, such as those 

 of the knee and lower jaw, to allow greater freedom of movement 

 whilst diminishing the liability to dislocation. Under the microscope 

 white fibro-cartilage looks very like fibrous tissue, but its cells are 



