CHAPTER VII 

 THE CONNECTIVE TISSUES 



Under this head are classn.jd Connective Tissue Proper, Carti- 

 lage, and Bone. 



General Characteristics. — The most prominent characteristic of 

 the connective tissues is the predominance of the intercellular sub- 

 stance. In this respect the connf^r' '^-e tissues differ markedly from 

 epithelium. IMoreover it is the 'I'-'^'^'srcellular substance and not 

 the cells which determines the physical character of the tissue. 

 Thus, for example, the hardness of bone and teeth, the firmness and 

 elasticity of cartilage, the toughness of tendon, the softness of sub- 

 cutaneous connective tissue, are all due to the character and arrange- 

 ment of the intercellular elements. In most forms of connective 

 tissue the cellular elements are very similar and in no way determine 

 the physical character of the tissue. 



The role of the connective tissues is mainly passive, and the 

 cells, instead of playing the most active part, as in epithelial, muscle 

 and nerve tissues, serve mainly for the maintenance of the nutrition 

 of the more important intercellular substance. The latter thus 

 predominates in function as well as in quantity, its character accord- 

 ing with the specific function of the tissue. Thus, where rigidity 

 and preservation of form are essential, are found connective tissues 

 with such intercellular substance as occurs in bone, where toughness 

 and elasticity, such types of intercellular substance as occur in tendon 

 and cartilage, where softness and flexibility, such loosely arranged 

 intercellular elements as are present in areolar tissue. 



Most of the connective tissues are extremely vascular, differing 

 also in this respect from epithehum. An exception to this rule 

 is hyalin cartilage. v 



A verj^ close relation exists between the different forms of connective tissue 

 as evidenced by a marked tendency and ability of one form to be closelj' united 

 to, or to be transformed into, or to be replaced by, another form. This may be 

 progressive in line of developmenl or retrogressive in line of degeneration. For 

 example the close physical union which exists between tendon and bone or 

 between cartilage and bone or tendon: or the manner in which the forms of bone 

 are first laid down in connecti\-e tissue, which is rei^laced by bone, or by cartilage 



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