22 ANATOMY OF THE RABBIT 



Mesothelium, mentioned on page 18 as a type of epithelium, is 

 related in embryonic origin (from mesenchyme) to connective 

 tissue. It consists of a single layer of extremely flattened cells 

 reinforced by some connective tissue fibres and cells. Endothelium 

 also could be classified here both on account of its origin from 

 mesenchyme and on account of the fact that its cells, though 

 squamous, may under certain conditions differentiate into connec- 

 tive tissue cells. 



Skeletal Tissues 



The skeletal tissues are solid forms of connective tissue which, 

 on account of their more permanent shape, are better adapted to 

 form a support for the body. They are of two kinds — cartilage 

 and bone. 



Simple or hyaline cartilage (Fig. 9) is a semi-solid and some- 

 what resilient material of a bluish or pearly coloration. It consists 



of a matrix which appears homo- 

 _ geneous unless certain special tech- 



-'772 niques are applied to it and in 



Q'^^ 



V;j 



,0. 



which the cells are imbedded. The 



^-'., ^te^iO' cells are distributed singly, or 



: 1^ ; *v^ f^ more often in groups of two to 



four, each cell, or occasionally two 



cells, being contained in a small 



oval space, the cartilage lacuna. 



The size of the spaces, and also 



their distance apart, are subject 



^ V to great variation. The presence 



il^X^fSonVT'iokJrSnt- of large numbers of white fibres 



IXut a?™:^„'a'ri.n;/v"uof ""^ . in the matrix produces a modi- 



fication known as fibro-cartilage. 

 This occurs in certain definite situations, as in the symphysis of 

 the pelvis, or in connection with the inter-articular menisci and 

 at the capsular margins of the joints. Elastic cartilages, such as 

 the epiglotic cartilage, contain many yellow fibres. 



The surface of the mass of cartilage (except the articular surfaces 

 within joint capsules) has a limiting membrane of fibrous connective 

 tissue, the perichondrium (Fig. 10) which develops new cartilage, 



