202 



SYNOVIAL MEMBEAXES. ' 



close investment to the tendon. The space betTveen these portions of 

 the membrane is kibricated with synovia and crossed obliquely by one 

 or more folds or duplications of the membrane, in some parts inclosing 

 elastic tissue (Marshall). These are named " frajua," and pass from 

 one part of the membrane to the other. 



Stnicture of synovial uiembranes. — The synovial membranes 

 are composed essentially of connective tissue with blood-vessels and 

 nerves. It was formerly stated that they were lined with an epithe- 

 lioid layer of flattened cells, similar to those lining the serous mem- 

 branes, but, as was shown by Hiiter, there exists on the synovial 

 membranes no complete lining of the kind. Patches of cells may, it 

 is true, here and there be met with which present an epithelioid 

 appearance (fig. 134, e), as, indeed, we know to be the case in the con- 

 nective tissue of other parts ; but most of the surface-cells of the 

 synovial membranes are of the irregularly-branched type (fig. 134, s), 

 the surface of the membrane between the cells and sometimes also over 

 them beimj formed by the ground substance of the connective tissue, 

 whilst here and there small blood-vessels come to the surface from 



Fiff. 135. 



Fig. 134. 



Fig. 134. — Cell-Si'aces from Synovial Surface of Tf.ndojj (Human). 340 Diameters. 

 e, part of an epithelioid patch ; s, more isolated, branched cell-spaces. The nuclei of 

 the cells are faintly indicated. 



Fig. 135. 



-Connective-Tissue Corpuscles from Articulae Synovial Membrane oi' 

 Ox. IVIagnified 250 Diametkus. 



the subjacent parts. The cells and cell-spaces of the synovial mem- 

 brane arc at many places considerably smaller than those of the connec- 

 tive tissue generally : this is owing to a scantiness in the amount of 

 protoplasm, the nuclei being of the usual size and often appearing 

 almost to fill the body of the cell. Sometimes the cell-spaces Avith 



