290 



SPECIAL HISTOLOGY. 



Fig. 124. 



in certain spots, of a yellowish-white color, with a silky lustre. Its 

 matrix in the latter situations presents a fibrous structure, and elsewhere 

 a finely granulated aspect. The outermost cells, to the depth of 0-06 

 0-1 of a line, are elongated, flattened, parallel to the surface, most 

 usually small (sometimes not more than 0-006 of a line), but sometimes 

 larger, and filled with one or even many secondary cells, one placed be- 

 hind the other ; more internally, without entirely losing their flattened 

 figure, they are larger (most of them 0-03-0-05 of a line), oval, and 

 round, and lie with their surfaces towards the ends of the cartilage, and 

 with their long axis for the most part in the direction of the radius of 

 the transverse section of the rib ; in many cases, however, they are dis- 

 posed more irregularly. The largest of these cells (measuring as much 

 as 0-08 or, even 0-1 of a line), are found in the fibrous spots, and they, in 

 common with all the interior cells, contain secondary cells, in varying, 

 frequently in very considerable number (as many as 60 according to 

 Ponders). The most remarkable characteristic of the elementary tissue 



of the costal cartilage is the 

 large quantity of fat con- 

 tained in it. In the adult, 

 every cell, excepting the 

 most superficial, contains, 

 larger or smaller (from 

 0-0016-0-008 of a line), 

 sometimes spherical, some- 

 times more irregular fat- 

 drops, which frequently so 

 surround the nucleus as en- 

 tirely to conceal it from 

 view (Fig. 124 a, 5), whence 

 it has been assumed, though 

 not quite correctly, that the 



fat is seated in the latter. The cartilage on the greater cornu of the 

 os hyoides, and between the body and the greater cornu, and the incon- 

 stant cartilaginous appendage to the styloid process, differ in no respect 

 from costal cartilage, only that the cartilage cells in those instances do 

 not always contain large fat-globules. 



The costal cartilages frequently become ossified in old age ; but this 

 ossification, as well as the fibrillation of the matrix, must not be re- 

 garded as a normal process, nor be placed in the same category with the 

 usual kind of ossification. The ossification is sometimes more limited, 



FiG. 124. Cartilage cells of Man, magnified 350 diameters: a, parent cell with three se- 

 condary cells containing oil, from a costal cartilage; 6, two cells from the same situation in 

 which the globule of oil is surrounded by a pale border; c, two cells with thickened walls 

 from the cartilage of the greater cornu of the os hyoides, which together with the globule of 

 oil also contain a distinct nucleus. 



