STRUCTURE OF CARTILAGE. 



133 



reference to its intimate structure it admits of classification into three 

 kinds, true cartilage, reticular cartilage, and fibrous cartilage. 



True Cartilage is composed of a semi-transparent homo- 

 geneous substance (hyaline or vitreous substance) contain- 

 ing a number of minute cells (cartilage corpuscles) dispersed 

 at short intervals through its structure. The cells are oval, 

 oblong, or polyhedral in shape, and more or less flattened 

 their membranous envelope is blended with the intercellular 

 substance, and they contain in their interior secondary cells, 

 nuclei, nucleoli, oil-globules, and more or less of granular 

 matter. Cartilage cells have an average measurement of 

 YsVft of an inch in their long diameter ; they are sometimes 

 isolated, sometimes grouped in pairs, and sometimes dis- 

 posed in a linear group of three or four. They are larger 

 near the bone than at the surface, and in the latter situation 

 are long and slender in form, and arranged in rows having their long axis 

 parallel with the plane of the surface. True cartilage is pearl-white or 

 bluish and opaline in colour, and its intercellular substance is semitrans- 

 parent and structureless. These characters, however, are changed when 

 it exhibits a tendency to ossify. In the latter case the intercellular sub- 

 stance becomes fibrous and more or less opaque, its colour is yellowish, 

 and the cells are found to contain a greater number of oil-globules than 

 in its natural state. 



The true cartilages are, the articular, costal, ensiform, thyroid, cricoid, 

 arytenoid, tracheal and bronchial, nasal, meatus auris, the pulley of the 

 trochlearis muscle, and temporary cartilage or the cartilage of bone pre- 

 viously to ossification.! 



Reticular cartilage is composed of cells ( T ^ of an inch in diameter), 

 separated from each other by an opaque, subfibrous, intercellular network, 

 the breadth of the cells being considerably greater than that of the inter- 

 cellular structure. The cells are parent cells, containing others of second- 

 ary formation, together with nuclei, nucleoli, granular matter, and oil- 

 globules in greater number than those of true cartilage. The fibres are 

 short, imperfect, loose in texture, and yellowish. The instances of reti- 

 cular cartilage are, the pinna, epiglottis, and Eustachian tube. 



Fig. 004 



Fig. G7. 



* A portion of articular cartilage near the synovial surface of an articulation,- the line 

 to the left is that of the synovial boundary. 



t Puire 47. 



* A portion of reticular cartilage. The section is taken from the pinna, and matfn, 

 fied 155 diameters. 



A portion of fibrous cartilage. The section is taken from the syinpliysis pubis, *a4 

 magnified 155 diameters. 



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