title: Electron microscope and biochemical observations of the surface active phospholipids on the articular surfaces and in the synovial fluid of the temporomandibular joint: a preliminary investigation.
abstract: OBJECTIVE
  The goal of this article is to investigate the surface-active phospholipids located on the articular surfaces and in the temporomandibular joint (TMJ) synovial fluid (SF) by means of electron microscopy and biochemical analysis.
  
  
  METHODS
  Synovial fluids and articular cartilage samples taken from 6 normally functioning TMJs were studied. The osmiophilic lining of human TMJ articular surfaces has been studied by using special nondestructive fixation procedures. To study the SF, negative staining technique has been used. In addition, thin-layer chromatography has been used to identify the phospholipids extracted from synovial fluid of human TMJs.
  
  
  RESULTS
  In the SF, granular bodies were identified with diameter of between 170 and 280 nm. Their diameter decreased dramatically when exposed to phospholipase-A(2). The amorphous and highly osmophilic material on the articular surface include membrane-bound vesicles (270 nm in diameter) with lamellated pattern surrounding the amorphous-dense core. Biochemical extraction revealed phosphatidylcholine as the major component of the polar lipids.
  
  
  CONCLUSIONS
  This preliminary study presents findings that suggest that phospholipids present in the TMJ may provide an efficient boundary lubrication that enables the disc to slide down the slope of the eminence on joint function.
authors.affiliation: Electron Microscopy Unit, Department of Electron Microscopy, The Hebrew University-Hadassah School of Medicine, Jerusalem, Israel.
authors.forename: E
authors.initials: E
authors.lastname: Rahamim
authors.forename: H
authors.initials: H
authors.lastname: Better
authors.forename: A
authors.initials: A
authors.lastname: Dagan
authors.forename: D W
authors.initials: DW
authors.lastname: Nitzan
mesh_terms: D002855:Chromatography, Thin Layer; D006801:Humans; D008153:Lubrication; D008246:Lysophospholipids / Q000032:analysis; D008563:Membrane Lipids / Q000737:chemistry / Q000502:physiology*; D008854:Microscopy, Electron; D010713:Phosphatidylcholines / Q000032:analysis; D010714:Phosphatidylethanolamines / Q000032:analysis; D010743:Phospholipids / Q000737:chemistry* / Q000502:physiology*; D022142:Secretory Vesicles / Q000648:ultrastructure; D013109:Sphingomyelins / Q000032:analysis; D013499:Surface Properties; D013582:Synovial Fluid / Q000737:chemistry*; D019224:Temporomandibular Joint Disc / Q000737:chemistry*
chemical_list: D008246:Lysophospholipids; D008563:Membrane Lipids; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010743:Phospholipids; D013109:Sphingomyelins