YELLOW FIBROUS TISSUE. 115 



The development of cartilage is the same with that of cartilage of 

 bone (page 5), the different forms of cartilage resulting from subse- 

 quent changes in the intercellular substance and cells. Thus, for 

 example, in articular cartilage the cells undergo the lowest degree of 

 development, are very disproportionate to the intercellular substance, 

 and the latter remains permanently structureless. In reticular carti- 

 lage the cells possess a more active growth, and surpass in bulk the 

 intercellular substance, while the latter is composed also of cells, 

 which assume a fibrous disposition. In fibrous cartilage development 

 is most energetic in the intercellular substance ; this is converted into 

 fasciculi of fibrous tissue while the interspaces are filled with cells and 

 imperfect fibrous tissue in every stage of development. 



FIBROUS TISSUE is one of the most generally distributed of all the 

 animal tissues ; it is composed of fibres of extreme minuteness, and 

 presents itself under three elementary forms ; namely, white fibrous 

 tissue, yellow fibrous tissue, and red fibrous tissue. 



In white fibrous tissue the fibres are cylindrical, exceedingly minute, 

 (about igooo of an inch in diameter), transparent and undulating ; 

 they are collected into small fasciculi (from - 3 ^ to 10 ^ 0o of an 

 inch) and these latter form larger fasciculi, which according to their 

 arrangement give rise to the production of thin laminae, membranes, 

 ligamentous bands, and tendinous cords. The connecting medium of 

 the fibres in the formation of the primitive fasciculi is a transparent 

 structureless interfibrous substance or blastema, to which in most 

 situations are added numerous minute dark filaments derived from 

 nuclei and thence termed nuclear filaments. The nuclear filaments are 

 sometimes wound spirally around the fasciculi or interlace with their 

 separate fibres, at other times they are variously twisted and run 

 parallel with the fasciculi. The fasciculi are connected and held to- 

 gether in the formation of membranes and cords by loose fibres which 

 are interwoven between them, or by mutual interlacement. 



Examples of white fibrous tissue are met with in three principal 

 forms, namely, membrane, ligament, and tendon. 



The membranous form of white fibrous tissue is seen in the common 

 connecting medium of the body, namely, fibro-cellular or areolar tissue, 

 in which the membrane is extremely thin and disposed in laminae, 

 bands or threads, leaving interstices of various size between them. 

 It is seen also in the condensed covering of various organs, as the 

 periosteum, perichondrium, capsulse propriae of glands, membranes of 

 the brain, sclerotic coat of the eyeball, pericardium, fasciae ; sheaths of 

 muscles, tendons, vessels, nerves and ducts ; sheaths of the erectile 

 organs, and the corium of the dermic and mucous membrane. 



Ligament is the name given to those bands of various breadth and 

 thickness which retain the articular ends of bones in contact in the 

 construction of joints. They are glistening and inelastic and com- 

 posed of fasciculi of fibrous tissue ranged in a parallel direction side 

 by side, or in some situations interwoven with each other. The 

 fasciculi are held together by separate fibres, or by areolar tissue. 



