i 4 PRACTICAL HISTOLOGY. 



CARTILAGE. 



IN every cartilage there fall to be considered (a) the matrix, and (V} the cartilage-cells or 

 corpuscles. Cartilages are classified according to the nature of the matrix. If the matrix be 

 clear and like ground-glass it is called hyaline cartilage ; if fibrous it is a fibro-cartilage, of 

 which there are two varieties : one, where the matrix resembles yellow elastic tissue, is yellow 

 fibro-cartilage, and the other, in which the fibres resemble white fibrous tissue, is white fibro- 

 cartilage. Where the cells are separated by a very small quantity of matrix, the cartilage is 

 said to be celhilar, as in the ear of a mouse or in the chorda dorsalis. 



HYALINE CARTILAGE 



Occurs in the articular ends of bones, cartilages of the ribs, part of the sternum, larynx, 

 trachea and bronchi, and some nasal cartilages. 



A. FRESH HYALINE CARTILAGE. Open any joint of an animal just killed, or take the 

 cartilage of a rib from the same animal and make a thin slice of the cartilage with a razor. 

 Place the thin slice in a drop of blood-serum or one per cent alum solution, cover and examine. 

 Instead of making a slice, a piece of cartilage sufficiently thin may be obtained from the 

 sternum of a newt or the tracheo-laryngeal cartilages of a frog. 



EXAMINATION (H). If a thin slice has been made, observe the hyaline matrix dotted 

 over with corpuscles, or cells the cartilage-cells. Study first the cartilage-corpuscles and 

 then the matrix. The corpuscles are oval or of various shapes, granular and containing a large 

 nucleus. The protoplasm of the cells fills the entire space or lacuna in which it lies, but 

 especially near the margin of the section the protoplasm may have fallen out of the lacunae, 

 or shrunk up so that it no longer completely fills the space in which it lies. By focussing 

 the cells are seen to lie in several planes. " The matrix is hyaline and perfectly homogeneous 

 in its appearance (PI. III., Fig. i). 



EFFECTS OF REAGENTS, (a) Water. Irrigate the section with distilled water. The 

 protoplasm of the cell now shrinks rapidly from the cavity containing it. It becomes 

 coarsely granular and thus often obscures the nucleus. 



(3) Iodine Solution. Make a transverse section of a costal cartilage of a young animal. 

 Stain with iodine solution for three to five minutes, add glycerine and examine (H). This 

 stains the matrix yellow, and the corpuscles of a deeper tint. Within the protoplasm a 

 brownish coloration may result, which indicates the presence of glycogen ; this is best seen in 

 young growing cartilage. 



B. METHODS OF PREPARING HYALINE CARTILAGE FOR PERMANENT PREPARA- 

 TIONS. It is necessary to use reagents to ' fix ' the structural elements of the cartilage, an d 



