Microfibrillar meshwork of the synovial lining and associated broad banded collagen: a clue to identity.
The surface layer of synovial interstitium lining the rabbit knee was studied by transmission electron microscopy. Over a distance of 2-3 microns normal to the surface the interstitium contained a network of fine microfibrils (diameter 9.3 (0.7) nm, mean (SEM] which was quite dense in places (fractional area of projection 0.189 (0.023], and stained with ruthenium red. Periodic collagen fibrils were relatively scanty and fine (diameter 32 (2) nm) in this surface layer. Broad cross-striated bundles occurred in association with the microfibrils and B cells. These fibrous long spacing bundles (FLS) had a single period of 92.8 (2.8) nm with a broad dark band (37.6) (1.8) nm--so called 'zebra collagen'. Both the periodicity of the FLS and the morphological characteristics of the microfibrils are typical of type VI collagen, a widespread constituent of soft connective tissues. The functional importance of the inner microfibril network is likely to be mechanical, biochemical (glycosaminoglycan and glycoprotein entrapment), and to a very minor degree hydraulic resistance.
Levick
J R
JR
Department of Physiology, St George's Hospital Medical School, London.
McDonald
J N
JN
D008841:Actin Cytoskeleton / Q000648:ultrastructure*; D000818:Animals; D003094:Collagen / Q000032:analysis*; D003599:Cytoskeleton / Q000648:ultrastructure*; D005121:Extremities; D008854:Microscopy, Electron; D011817:Rabbits; D013583:Synovial Membrane / Q000648:ultrastructure*
D003094:Collagen