HYALINE CARTILAGE. 



Ixxxiii 



from that of the synovial membrane, a thin stratum of areolar tissue 

 being interposed ; but the existence of such a covering is certainly not 

 general, at least in the 



adult. It is easy, no p-^ XLI. 



doubt, to peel off a thin 

 film from the surface of 

 the cartilage of the head 

 of the humerus or femur ; 

 but this superficial layer 

 is really part of the car- 

 tilage, and its broad 

 patches of cells with the 

 intermediate matrix are 

 not to be mistaken. (See 

 fig. XL.) At the same 

 time, it is true that near 

 the margin of these car- 

 tilages a layer of fine 

 filamentous tissue, co- 

 vered with epithelium, 

 is prolonged a certain 

 way over their surface 

 from the synovial mem- 

 brane. The matrix of 

 articular cartilage rarely, 

 or perhaps never, be- 

 comes pervaded by 

 fibres like those so often 

 seen in rib-cartilage, nor 

 is it prone to ossify. 



In the cartilages of the ribs, the corpuscles or cells, which are of large size, 

 are also collected in groups. Near the exterior of the cartilage they are 

 flattened, and lie parallel with the surface, forming a superficial stratum 

 from i-jy to 3 n of an inch thick. As to those situated more inwardly, we 

 can sometimes observe, in a transverse slice, that they form oblong groups 

 disposed in lines radiating to the circumference ; but this arrangement is 

 not constant, and they often appear quite irregular. The cells, with the 

 exception of those lying upon the surface, commonly contain larger or 

 smaller drops of oil ; and the nucleus, being generally undiscoverable, is 

 concealed by the fat or may itself have undergone a fatty metamorphosis. 

 The matrix is tolerably clear, except where fibres have been developed in it, 

 in which parts it is opaque and yellowish. Such fibrous patches are very 

 frequent ; the fibres are fine, straight, and parallel, appearing transparent 

 when few together ; they withstand the action of acetic acid. It is not un- 

 common to find the rib-cartilages extensively ossified. 



It was observed by Herissant * that the costal cartilages, after many 

 months' maceration in putrid water, would sometimes break up into thin 

 plates, directed across the axis of the cartilage ; from which he inferred 

 that these cartilages were naturally made up of such transverse lamellae : 

 but the point does not appear to have been further investigated. 



The description given of the microscopic characters of the costal cartilages 

 will apply with little variation to the ensiform cartilage of the sternum, to 



* Mem. de 1'Acad. des Sc. de Paris, 1748. 



Fig. XLI. VKRTIOAL SECTION OP ARTICULAR CARTILAGE 

 OF TUB HEAD OP THE HUMERUS. 



A deep portion near the bone. Magnified 400 dia 

 meters. Each cell-cavity contains a mass shaped like 

 itself, the shrunken cell- body, in the midst of which a 

 round nucleus is probably concealed. 



