180 MANUAL OF HISTOLOGY. 



Among the cartilages of the human body which have a thoroughly 

 solid reticular intercellular substance, may be numbered certain portions 

 of the respiratory apparatus, namely, the epiglottis, the cartilages of 

 Wrisb&rg and Santorini, the Eustachian tube and pinna of the ear. 

 Further, as having a partially fibrous blastema, the arytenoid cartilages 

 and intervertebral ligaments. 



109. 



We have now to enter on the consideration of a third species of this 

 tissue, namely, of the connective-tissue cartilage, or, as it has been less 

 happily termed, fibro-cartilage (fig. 171). This may be looked upon 

 as a hyaline cartilage whose abundant matrix has developed into fasci- 

 culi of connective-tissue, or as a solid species of the latter, through 

 which cartilage cells are scattered. The fact is that it is usually a 

 mixture of connective-tissue and cartilage. Like connective-tissue, it 

 contains elastic fibres as well as the cells of this tissue, known as con- 

 nective-tissue corpuscles. Between the latter and many cartilage cells 

 there occur intermediate forms, so that fibro-cartilage may pass into 

 ordinary connective-tissue without any line of demarcation, especially at 

 those points at which it becomes poor in cells. 



^ n ^ ie ot ^ er hand, its bearing as a 

 cartilage, with connective-tissue matrix, 

 appears clearly in the intervertebral liga- 

 ments, where we find close to portions 

 which are hyaline in texture other points 

 where the matrix is obscurely fibrous, and 

 continuous with a substance which is evi- 

 dently connective-tissue. 



Fibro-cartilage, which is brought espe- 

 cially into use in the construction ^of 

 joints, appears to the unaided eye of 

 whitish or slightly yellow colour, and to 

 possess a texture sometimes solid and 

 sometimes rather soft. It is more exten- 

 s ^ le > furtn er, than ordinary cartilage. 



Under the microscope we find, instead 

 of the homogeneous matrix of hyaline cartilage, connective-tissue with 

 fibres sometimes more indistinct than at other times, when they may 

 be very sharply defined. The bundles are usually crossed in all direc- 

 tions confusedly. They may, however, preserve some definite direction on 

 the other hand, while their optical and chemical bearing is quite that of 

 ordinary connective-tissue (see below). As to the cartilage cells, their 

 proportion is in general but small, and frequently, indeed, very incon- 

 siderable, so that they require to be searched for. The size, further, 

 of the ^ cells is also small, and their whole constitution simple, the out- 

 line being usually very delicate, and the nucleus, as a rule, single. Cells 

 with two nuclei are rare, and those containing daughter-cells apparently 

 do not occur at all. Fatty infiltration likewise, which is so common in 

 other species of cartilage, is here of rare occurrence. The position of 

 the cells is also liable to variation. They are either without arrange- 

 ment or crowded together in small groups, or again, arranged one after 

 another in rows. The latter position corresponds with the direction of 

 the fibres of the tissue. 



