44 



ELEMENTARY TISSUES. 



FIG. 14. 



1. Cellular cartilage may be readily obtained from the ex- 

 ternal ear of rats, mice, or other small mammals. It is com- 

 posed almost entirely of cells (hence its name), with little or no 

 matrix. The latter, when present, consists of very fine fibres, 

 which twine about the cells in various directions and inclose 



them in a kind of network. 

 The cells are packed very 

 closely together, so much so 

 that it is not easy in all cases 

 to make out the fine fibres 

 often encircling them. 



Cellular cartilage is found 

 in the human subject, only 

 in early foetal life, when it 

 constitutes the Chorda dorsalis. 

 (See chapter on Generation.) 

 2. Hyaline cartilage is met 

 with largely in the human 

 body, investing the articular 

 ends of bones, and forming 

 the costal cartilages, the nasal 

 cartilages, and those of the 

 larynx, with the exception of 

 the epiglottis and cornicula 

 laryngis. Like other carti- 

 lages it is composed of cells 

 imbedded in a matrix (Fig. 14). 

 The cells, which contain a nucleus with nucleoli, are irregu- 

 lar in shape, and generally grouped together in patches. The 

 patches are of various shapes and sizes, and placed at unequal 

 distances apart. They generally appear flattened near the free 

 surface of the mass of cartilage in which they are placed, and 

 more or less perpendicular to the surface in the more deeply 

 seated portions. 



The matrix in which they are imbedded has a dimly granu- 

 lar appearance, like that of ground-glass. 



In the hyaline cartilage of the ribs, the cells are mostly 

 larger than in the articular variety, and there is a tendency to 

 the development of fibres in the matrix. The costal cartilages 

 also frequently become ossified in old age, as also do some of 

 those of the larynx. 



Temporary cartilage closely resembles the ordinary hyaline 

 kind ; the cells, however, are not grouped together after the 

 fashion just described, but are more uniformly distributed 

 throughout the matrix. 



Articular hyaline cartilage is reckoned among the so-called 



A thin layer peeled off from the sur- 

 face of the cartilage of the head of the 

 humerus, showing flattened groups of 

 cells. The shrunken cell-bodies are dis- 

 tinctly seen, but the limits of the capsu- 

 lar cavities, where they adjoin one 

 another, are but faintly indicated. Mag- 

 nified 400 diameters (after Sharpey). 



