FIBRO-CARTILAGE. 



261 



Fibro-cartilages dry readily when exposed 

 loathe air and become of a deep yellow colour ; 

 they resist for a very long time, many months, 

 the influence of maceration, and by Long-con- 

 tinued boiling they become converted into a 

 gelatinous substance. Their chemical compo- 

 sition is said to be made up of albumen, phos- 

 phate of lime, chlorurets of sodium and of 

 potassium, sulphate of lime and other salts, 

 usually found in animal textures. 



The microscopic characters of nbro-cartilage 

 do not seem to have been investigated with the 

 same care as those of many other textures. I 

 have examined by transmitted light very thin 

 slices of the fibro-cartilages in the knee and 

 temporo-maxillary joint, and the appearance 

 presented was uniformly that of a very compli- 

 cated cellular structure, composed of minute 

 meshes, very irregular in size and shape. In 

 examining the intervertebral substance I have 

 distinctly seen, towards the circumference of 

 the disc, those fine and uniform cylindrical 

 fibres with wave-like bendings described and 

 figured by Jordan ;* but towards the centre the 

 texture exhibited the cellular appearance with 

 larger meshes, similar to that seen in the fibro- 

 cartilages of the knee and joint of the lower 

 jaw.f 



Of the structures placed by Bichat among 

 the fibro-cartilages, some have been considered 

 by Meckel, Beclard, Weber, and other anato- 

 mists to be pure cartilage, and as it seems to 

 me with much justice. These are the membra- 

 niform cartilages of the external ear, Eustachian 

 tube, nose, larynx, trachea, and eyelids. The 

 cartilaginous nature of most of these textures 

 is very apparent upon carefully dissecting off 

 the dense perichondrium which invests them, 

 and to which, doubtless, they owe their flexi- 

 bility, or more correctly, by which they are 

 prevented from being fractured under the 

 influence of a bending force. Careful micro- 

 scopic observation may assist materially in 

 affording marks indicative of pure cartilage ; 

 and as the observations of Purkinje, Miiller, 

 and Miescher approach in some degree to this 

 object, I have thought it not foreign to the 

 subject of this article to introduce here some 

 account of these researches. The results of 

 Purkinje's examinations of the minute structure 

 of bone as well as cartilage were published in 

 the year 1834 in an inaugural dissertation by 

 Deutsch.t Miiller and Miescher have further 

 investigated the subject and confirmed the 

 statements of Purkinje. 



In examining thin slices of cartilage under 



* Uber das Gewebe der Tunica Dartos, &c. 

 Mullet's Archiv, 1834. 



t Miescher states that in infants this part of the 

 intervertebral substance is composed of a pellucid 

 mucus, vrhich, under the microscope, sometimes 

 exhibits some of the cartilaginous corpuscles to be 

 noticed in a subsequent part of this article, but in 

 adults it is composed of adipose tissue! 



$ De penitiori ossium structura. Diss. inaug. 

 Vratisl. 1834. 



Vid. Miiller, Vergleichende Anatomic der 

 Myxinoiden, Berlin, 1835, and Miescher, de ossium 

 genes , structura, et vita. Diss. inaug. Berol. 



Fig. 139. 



the microscope by transmitted light, Purkinje 

 observed numerous little bodies irregularly dis- 

 persed through its texture, of a round or oval 

 form, and somewhat less transparent than the 

 intervening substance. The annexed figure, 

 taken from Miiller's work 

 already referred to, gives 

 a representation of these 

 bodies : they are deno- 

 minated by Purkinje 

 cartilaginous corpuscles 

 ( Knorpel Korperchen}. 

 In some cases, as in tem- 

 porary cartilage, they ap- 

 peared to consist of mi- 

 nute granules ; they pre- 

 sented this appearance 

 likewise in the cartilagi- 

 nous part of the cranium 

 of a frog. In the costal 

 cartilages they were solid, 

 and in the cartilaginous 

 fishes, as in the lamprey, 

 their contents were of a 

 soft or fluid consistence. According to Purkinje, 

 these corpuscles are found in the temporary 

 cartilages, in permanent cartilage, in cartilage 

 which becomes ossified in old age, as that of 

 the ribs and larynx, in the cartilages of the 

 nose and septum narium. 



According to Miescher there are two kinds 

 of permanent cartilage, differing from each 

 other as well by external characters as by in- 

 ternal structure ; one of these scarcely differs 

 at all from the temporary cartilage, the other 

 is very dissimilar in structure. The first class 

 is at once distinguished by its azure whiteness 

 and by its pellucid brightness, not unlike that 

 of mother-of-pearl, from the second, which is 

 yellowish in colour, not pellucid, and spongy 

 in texture. To the former class belong all 

 articular cartilages, those of the ribs,* that of 

 the ensiform cartilage of the sternum, the thy- 

 roid, cricoid, and arytenoid cartilages, and 

 those of the septum narium and alae nasi. 

 All the cartilages of this class are characterized 

 by containing the microscopic corpuscles above 

 described, variously arranged in each form of 

 cartilage, in some placed in clusters, in others 

 closely aggregated together in one part and 

 separated in another. It is interesting to ob- 

 serve that the temporary cartilage universally 

 contains these corpuscles, and as all the carti- 

 lages we have described are more or less prone 

 to ossification in advanced age, we are led to 

 the inference, that these corpuscles thus de- 

 posited are characteristic of cartilage which 

 admits of becoming ossified.f 



* Sic Miescher. 



t The cartilages most liable to ossify by the pro- 

 gress of age in man, are those which most fre- 

 quently exhibit, after a certain period, a per- 

 manently ossified condition in some of the inferior 

 classes of animals. Thus, in birds, and among 

 mammals, inmonotremata,cheiroptera,and cetacea, 

 the cartilages of the ribs show a very early dis- 

 position to ossify. In birds the laryngeal cartilages 

 are very apt to ossify, and in swine and oxen par- 

 tial ossifications of the same cartilages are not 



