298 



SPECIAL HISTOLOGY. 



Fig. 128. 



Within the synovial capsules is contained, in small quantity, a clear 

 yellowish fluid, which may be drawn out into threads, the synovia, 



and which, in its chemical composition, ap- 

 pears very closely to resemble mucus, and 

 particularly in its containing mucin in solu- 

 tion. Examined under the microscope, in its 

 normal condition, this secretion exhibits no- 

 thing worthy of much remark, consisting simply 

 of fluid which is rendered turbid by acetic 

 acid, and very frequently contains epithelial 

 cells, which have often undergone a fatty meta- 

 morphosis, nuclei of such cells, and fat globules ; 

 under conditions not quite normal, it may also 

 contain blood- and lymph-corpuscles, detached 

 portions of the synovial processes of the arti- 

 cular cartilage, and a structureless gelatinous 

 substance. 



The normal, healthy synovia, which in the Ox. according to Frerichs 

 (Wagn. " Handb." III. 1), contains 94'8 water, O5 mucus and epithe- 

 lium, 0'07 fat, 3*5 albumen and extractive matter, and 0*9 salts, is a 

 secretion, not having essentially any formed elements in it, which 

 simply exudes from the vessels of the synovial membrane with the inter- 

 mediation of the epithelium ; and, in fact, from all its vascular processes, 

 which are destined as it were for this special function, and always exist 

 at the border of a cartilage requiring a lubricating covering. The non- 

 vascular appendages of these processes give origin to the " loose carti- 

 lages," as they are termed ; they do this by their increasing in size and 

 solidity, and becoming detached from the vascular folds. These bodies 

 are also met with in mucous bursse and the sheaths of tendons, which 

 are also furnished with vascular folds (vid. sup. 82) ; they consist of 

 connective tissue with elongated nuclei, coated with epithelium, and, 

 though not always, contain a variable number of scattered fat- and true 

 cartilage-cells ; and they are not developed externally to the synovial 

 membrane, but from an outgrowth of that membrane itself. Similar 

 solid bodies, moreover, may probably be produced in other ways ; 

 Bidder ("Zeitsch. f. rat. Medicin," vol. iii., p. 99, et seq.\ at all events, 

 and Virchow ("Med. Zeitung," 1846, Nos. 2 and 3) have observed 

 similar bodies presenting no trace of organization. I am inclined, with 

 Virchow, who has actually demonstrated the presence of fibrin in them, 

 to regard them, in many cases, as fibrinous exudations, and in others as 



Fia. 128. From the falciform ligament of the knee: a, a filament of connective tissue 

 with oval cells disposed in a series, and resembling cartilage-cells; b, a similar filament 

 with more elongated cells and nuclei. 



