HYALINE CARTILAGE. 51 



Hyaline cartilage occurs principally in two situations namely (1) 

 covering the ends of the bones in the joints, where it is known as 

 articular cartilage ; and (2) forming the rib-cartilages, where it is known 

 as costal cartilage. It also forms the cartilages of the nose, the external 

 auditory meatus, the larynx, and the windpipe ; in these places it serves 

 to maintain the shape and patency of the orifices and tubes. 



Articular cartilage. The cells of articular cartilage are mostly 

 scattered in groups of two or four throughout the- matrix (fig. 57). 

 The latter is free from fibres, except at the extreme edge of the 



FIG. 57. ARTICULAR CARTILAGE FROM HEAD OF METATARSAL BONE OF MAN 

 (OSMIC ACID PREPARATION). THE CELL-BODIES ENTIRELY FILL THE SPACES 

 IN THE MATRIX. (340 diameters. ) 



a, group of two cells ; b, group of four cells ; h, protoplasm of cell, with y, fatty granules ; 



n, nucleus. 



cartilage, where the connective-tissue fibres from the synovial membrane 

 extend into it ; and here also the cartilage-cells are often branched, and 

 offer transitions to the branched connective-tissue corpuscles of that 

 membrane (transitional cartilage, fig. 58). By long maceration, however, 

 evidence of a fibrous structure may be obtained, even in the matrix of 

 true hyaline cartilage. Some histologists also describe fine communica- 

 tions in the matrix uniting the cartilage-cells with one another, but 

 these are of doubtful occurrence. 



