66 



NORMAL HISTOLOGY. 



FIG. 51. 



Hyaline cartilage. Section from 

 human thyroid cartilage. 

 (Wolters.) a, perichondrium ; 

 b, peripheral zone of cartilage 

 with flattened cells. In the 

 deeper portions of the car- 

 tilage the cells are larger, are 

 arranged in groups, and are 

 surrounded by recently 

 formed matrix. The cells in 

 the deepest portions of the 

 cartilage are vacuolated, and 

 about the groups of cells are 

 fine granules of lime salts. 

 In the matrix are numerous 

 anastomosing lines, which are 

 interpreted as fine canals, serv- 

 ing to carry nourishment to 

 the cells in the cartilage. 



tion some of the cells 



typical of cartilage until the distinction 

 between the two tissues is lost. The peri- 

 chondrium is wanting over the free surfaces 

 of the articular cartilages. 



1. Hyaline Cartilage (Figs. 49, 50, and 

 51). Although under ordinary powers of 

 the microscope and in specimens which 

 have not been specially prepared the 

 matrix of hyaline cartilage appears clear 

 and almost, if not quite, homogeneous, 

 closer study reveals the presence of a fine 

 network within the clear intercellular sub- 

 stance. This network is thought to be a 

 system of minute channels through which 

 the nutrient fluids permeate the tissue 

 and reach its cells. It may be, however, 

 that this reticulum is of fibrous character^ 

 in which case the fibres might be more 

 pervious than the surrounding matrix, and 

 bear the same relations to the nutrition of 

 the tissue as a system of minute channels. 

 In sections stained with hsematoxylin the 

 matrix of hyaline cartilage often acquires a 

 faint bluish tinge, the cytoplasm of the 

 cells a deeper shade of the same color ? 

 and the nuclear chromatin a very dark 

 blue. 



Hyaline cartilage forms the costal car- 

 tilages, the thyroid cartilage, the ensiform 

 process of the sternum, the cartilages of 

 the trachea and bronchi, and the tem- 

 porary cartilages which are subsequently 

 replaced by bone. 



2. Fibro-cartilage (Fig. 52). This va- 

 riety of cartilage is found in only a few 

 situations : in the interarticular cartilages 

 of joints, in some of the synchondroses, 

 in one region in the heart, and in the 

 intervertebral disks. In the latter situa- 



possess branching processes, extending for 



