CARTILAGE. 3I 



cell is extensive, the nucleus may contain minute oil-globules. Although 

 many connective tissue elements become transformed into fat-cells at later 

 periods, the earliest adipose tissue in some localities, as beneath the skin 

 and in the orbit and omen turn, is developed from highly vascularized lobular 

 groups of mesenchymal cells (the fat organs of Toldt) which seem to be set 

 apart for the production of such tissue. During prolonged fasting and 

 extreme emaciation the fat-cells may lose the greater part, or even their 

 entire quota, of oily contents, which is then often replaced by a thin viscid 

 cytoplasm that distinguishes the so-called serous fat-cells. In other cases, 

 after the disappearance of the oil-drops the fat-cells return to a condition 

 closely resembling that of the ordinary connective tissue cell. 



CARTILAGE. 



Cartilage includes a group of supporting tissues in which the intercellu- 

 lar substance undergoes increasing condensation until, as the hyaline variety, 

 the intercellular matrix appears homogeneous, the constituent fibres being 

 so compact and closely blended that the fibrous structure is ordinarily no 

 longer appreciable. ^ 



Depending upon the *'"-^S=^ 

 differences exhibited by 

 the intercellular matrix, 

 three varieties of cartilage 

 are recognized, fyyaline, 

 fibrous and elastic. 



Hyaline cartilage, 

 or gristle (Fig. 45), is 

 widely distributed, form- 

 ing the articular surfaces 

 of the bones, the costal 

 cartilages, the larger carti- 

 lages of the larynx and 

 the cartilaginous plates of 

 the trachea and bronchi, 

 the larger cartilages of the 

 nose and the middle part 

 of the Eustachian tube. 

 In the embryo the entire 

 skeleton, with the excep- 

 tion of part of the skull, is 

 mapped out by primary 

 hyaline cartilage. 



The intercellular ma- 

 trix is apparently homo- 

 geneous, but after appropriate treatment it is resolvable into bundles of 

 white fibres; ordinarily, however, these are so closely united and blended by 

 the cementing ground-substance that the presence of the component fibres 

 is not evident. The cartilage-matrix is chemically complex, consisting of a 

 mixture of collagen, chondro-mucoid and albuminoid substances. 



The cartilage-cells, as the connective tissue elements within the matrix 

 are called, are irregularly oval or spherical nucleated bodies. They are 

 lodged within the interfascicular spaces, or lacuna, which they almost or 

 quite fill. In adult tissue usually two or more cells share the same compart - 







- 



-Perichondrium 



_Young 

 "cartilage-cells 



_Group of older 

 cells 



artilage-cells 



Lacuna con- 

 -taining nest of 

 cells 



Empty lacuna 

 surrounded by 

 hyaline matrix 



FIG. 45. Transverse section of peripheral portion of costal 

 cartilage. X 250. 



