176 MANUAL OF HISTOLOGY. 



and cricoid, but only partly in the c. arytenoidea. Again, in the half rings 

 of the trachea and bronchi, as well as in the costal cartilages, and ensi- 

 form process of the sternum. Finally, in the symphyses, and equivalent 

 Ugamenta intervertebralia. a thin layer immediately in contact with the 

 bone is to be found, which consists of genuine cartilaginous matter with 

 homogenous intercellular substance. 



Of the numerous parts formed of this tissue some deserve special notice. 



The rudimentary cartilaginous skeleton of the foetus presents at first 

 small roundish simple cells, closely crowded together, with vesicular 

 nuclei, and situated in a scanty soft ground-substance. Should such 

 a cartilage have reached an age at which it is about to fall a prey to 

 advancing ossification, the intercellular matter is seen to have consider- 

 ably increased. The cells have also increased in size, especially towards 

 the line of commencing ossification, at the same time that their capsules 

 cannot be said to have become thickened. Endogenous multiplication 

 has produced here a large increase also in their number. The daughter 

 cells so formed are now, as the saying is, free, in that the capsule of the 

 parent-cell is merged into the ground-substance, which is either homo- 

 geneous, fibrous, or streaky. They now lie either in long rows one 

 after another, frequently compressed into an obliquely oval form, as in the 

 middle portion of a growing hollow bone (in the so-called "direction" of 

 cartilage-cells), or they appear in irregular groups, as in the epiphyses 

 and short bones. The cartilage has now become vascular besides. 



Articular cartilages are thin coverings for the ends of bones entering 

 into the formation of joints. When firmly united to the bone at their 

 under surface, they represent the remainder of the original rudimentary car- 

 tilage, which has not given way to the encroachments of ossification. Their 

 superficial portions, lying free in the cavity of the joint, contain small but 

 strongly flattened cartilage cells measuring O'Ol 13-0*01 78 mm., crowded 

 one over the other, in a way that reminds ITS (when seen in vertical sec- 

 tion) somewhat of laminated epithelium. Further down, or at a greater 

 depth, we see the cells in the growing substance separated somewhat 

 more widely from one another. They lose at the same time the flat- 

 tened appearance, becoming taller and larger, increasing to 0-0156- 

 0-0282 mm. and upwards, with nuclei of from 0'0065-0'0090 mm. At 

 first they are piled without arrangement in heaps over one another; but 

 deeper in the vicinity of the bone, they group themselves into long rows, 

 perpendicular to the surface of the latter. The remainder is made up of 

 beds of calcified matter. In the large cells of articular cartilage, daughter- 

 cells are frequently present, while fatty globules are occasionally, but 

 rarely met with. 



The costal cartilages have been frequently described by histologists as the 

 best examples of hyaline structure, but incorrectly so on account of their 

 various transformations. In the new-born infant there appear in a com- 

 pletely homogeneous ground-substance (fig. 167) beds (a] of small cells 

 (parallel with the surface) like rents in the matrix, which have a delicate 

 outline, and which contain nuclei of about 0-0056 mm. in diameter. The 

 length of these cells is 0'0095-0'0150 mm. 



Their contents are either quite transparent or dotted with a few very 

 minute oil-globules of about 0*0018 mm., or even less in diameter. More 

 internally we encounter a number of generally narrow oval cells, some- 

 times reniform or wedge-shaped, placed in every position as regards one 

 another, while in the deepest portions of the costal cartilages, the largest and 



