102 



THE TISSUES 



CARTILAGE 



Cartilage is a form of connective tissue in which the ground sub- 

 stance is firm and dense and determines the physical character of the 

 tissue. On boiling it yields chondrin. Cartilage cells are differen- 

 tiated connective-tissue cells. While varying greatly in shape they 

 are most frequently spherical or oval. Each cell lies in a cell space 

 or lacuna, which it completely fills. The intercellular substance im- 

 mediately surrounding a lacuna is frequently arranged concentrically, 

 forming a sort of capsule. Fine canaliculi connecting the lacuna} are 

 present in some of the lower animals and have been described in 

 human cartilage. They can be demonstrated, however, in human 

 cartilage, only by special methods, and probably represent artefacts. 



Cartilage contains no blood-vessels, and in human cartilage no 

 lymph channels have been positively demonstrated. 



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Fig. 48. — Hyaline Cartilage from Head of Frog's Femur. X350. (Technic i, p. 

 104.) (Jroups of cartilage cells in apparently homogeneous matrix. 



Cartilage is subdivided according to the character of its intercellu- 

 lar substance into three varieties: (i) Hyaline, (2) elastic, (3) fibrous. 



I. Hya ine Cartilage (Fig. 48). — The cells occur singly or in groups 

 of two or multiples of two. An entire group of cells frequently lies 

 in one lucuna surrounded by a single capsule. Such a group of cells 

 has developed within its capsule from a single parent cell. In other 

 cases delicate hyaline partitions separate the cells of a group. The 

 cells are spherical or oval, with flattening of adjacent sides. The 

 nucleus i.s centrally placed, and has a distinct intranuclear network and 



