1 82 OSSEOUS SYSTEM. [sect. 95. 



joints. They consist almost solely of small arteries and veins, 

 with capillaries connected at the borders of the processes in form 

 of loops, and hence strikingly resemble the choroid plexus in the 

 cerebral ventricles. Along with the vessels, they contain a 

 fundamental connective tissue, often indistinctly fibrous ; they are 

 covered with an epithelium like that of the synovial membrane, 

 and occasionally include fat-cells in smaller or larger numbers, and 

 more rarely isolated cartilage-cells. On their border they almost 

 invariably bear small, leaf-like, conical, membranous processes, of 

 the strangest forms (often resembling a cactus-stem), which rarely 

 contain vessels, and consist, for the most part, only of an indis- 

 tinctly fibrous connective tissue along their axis, with, occasionally, 

 one or two cartilage-cells and an epithelium very thick in some 

 places. The smaller forms frequently consist only of epithelium, 

 or almost solely of connective tissue. 



The inter-articular cartilages or ligaments, and the ligaments of 

 the joints, consist, with the exception of the soft lig amentum teres, of 

 a firm connective tissue, with plasm-cells and fine elastic fibres, and 

 occasionally, also, cartilage-cells, especially in the case of the first- 

 mentioned structures. The synovia consists of a fluid containing 

 mucus, and becomes turbid on the addition of acetic acid. It 

 contains very frequently some epithelial cells which have undergone 

 the fatty degeneration, the nuclei of such cells and compound 

 granular cells. In conditions not entirely normal, blood and 

 lymph corpuscles, and detached portions of the synovial fringes 

 and articular cartilages, together with an amorphous gelatinous 

 substance, are found in it. 



The appendages of the synovial fringes, enlarging in size and acquiring a 

 firmer consistence, may become detached from their connection, and thus 

 give origin to certain forms of the so-called loose cartilages of joints. These, 

 which also occur in the synovial bursre and the sheaths of tendons, where, as 

 well as in joints, the vascular processes exist, consist of connective tissue 

 with elongated nuclei and a covering of epithelium, and contain, though not 

 in all cases, a variable number of scattered fat -cells and true cartilage-cells. 

 They are not developed externally to the synovial membrane, but are excre- 

 scences of the membrane itself. Moreover, it is probable that loose solid 

 bodies may arise in another manner ; at least, Bidder and Yirchow have 

 observed such bodies, which exhibited no trace of organised structure. I am 

 disposed, with Virchoro, to regard many examples of these latter, in which he 

 has actually demonstrated fibrin, as consisting of fibrinous exudations, and 

 others as consolidated precipitates from the synovia ; and the latter ex- 

 planation is supported by the fact of the frequent occurrence of amorphous 

 gelatinous masses, of greater or less consistency in the tendinous sheaths of the 

 hand, which concretions are evidently inspissated synovia. Pieces of bone, 



