Ixxxii 



HYALINE CARTILAGE. 



having the cell-bodies within. The effect of acids is promoted by previous boiling 

 of the cartilage in water. By exposure to water and some other liquids the cell- 

 body shrinks away from the inside of the capsule, and assumes a jagged or other- 

 wise irregular figure, and then may hide the nucleus. It often contains larger or 

 smaller fat-globules. 



The cells are rarely dispersed singly in the matrix ; they usually form 

 groups of different shapes and sizes. Towards the surface of the cartilage 

 the groups are generally flattened conformably with the surface (fig. XL.), 

 appearing narrow and almost linear when seen edgeways, as in a perpendi- 

 cular section. (Fig. xxxix., a.) The cells in a group have a straight out- 

 line where they adjoin or approach one another, but at the circumference of 

 the group their outline is rounded. 



Such is the structure of hyaline cartilage in general, but it is more or less 

 modified in different situations. 



Fig. XXXIX. Fig. XL. 



V & 





Fig. XXXIX. DIAGRAM REPRESENTING A VERTICAL SECTION OF ARTICULAR CARTILAGE, 



SEEN WITH A LOW MAGNIFYING POWER. 



a, Flattened groups of cells near the surface ; &, oblong groups, for the most part 

 directed vertically ; c, part of the bone. 



Fig. XL. A THIN LAYER PEELED OFF FROM THE SURFACE OF THE CARTILAGE OF THE 

 HEAD OF THE HUMERUS, SHOWING FLATTENED GROUPS OF CELLS. 



The shrunken cell-bodies are distinctly seen, but the limits of the capsular cavities 

 where they adjoin one another are but faintly indicated. Magnified 400 diameters. 



In articular cartilage, the matrix in a thin section appears dim, like 

 ground glass, and has an almost granular aspect. The cells and nuclei are 

 small. The groups which they form are flattened at and near to the surface, 

 and lie parallel with it (fig. xxxix., a, and fig. XL.) ; deeper and nearer 

 the bone, on the other hand, they are narrow and oblong, like short strings 

 of beads, and are mostly directed vertically. (Fig. xxxix., 6, fig. XL.) It 

 is well known that articular cartilages readily break in a direction per- 

 pendicular to their surface, and the surface of the fraolure appears to the 

 naked eye to be striated in the same direction, as if they had a columnar 

 structure ; this has been ascribed to the vertical arrangement of the 

 rows of cells, or to a latent fibrous or columnar disposition of the sub- 

 stance of the matrix (Leidy). It was formerly held that the free 

 surface of articular cartilage is* covered with epithelium continued 



