title: Electron-microscopic imaging of endothoracic fascia in the thoracic paravertebral space in rats.
abstract: OBJECTIVE
  Anesthesia and analgesia with paravertebral block are reportedly variable. Existence of an endothoracic fascia has been proposed as one of the possible mechanisms leading to variability. We undertook an electron-microscopy imaging study to investigate the endothoracic fascia in the thoracic paravertebral space (TPS) in rats.
  
  
  METHODS
  Male Wistar rats were studied in accordance with the principles of laboratory animal care. After the rats were euthanized in a CO2 chamber, the thoracic paravertebral tissues were removed en bloc and cut into consecutive transverse sections of approximately 3 mm. Stereomicroscopy and electron-microscopy assessments were performed by 2 independent observers.
  
  
  RESULTS
  The endothoracic fascia was consistently identified in all specimens. The fascia was located between the parietal pleura and the innermost intercostal muscles or ribs. Its thickness ranged from 15 to 27 μm (mean, 20 ± 3 μm). The endothoracic fascia divided the TPS in 2 compartments: one, extrapleural and anterolateral (EPC); another, subendothoracic and posteromedial (SETC). The spinal nerves with their ganglia were found within SETC, whereas the sympathetic ganglia were consistently located within the EPC.
  
  
  CONCLUSIONS
  The endothoracic fascia in rats appears to divide the TPS into EPC and SETC. These anatomic characteristics may have implications in thoracic paravertebral blockade.
authors.affiliation: Department of Anesthesiology and Intensive Therapy, University Medical Center Ljubljana, Ljubljana, Slovenia. tatjanas38@gmail.com
authors.forename: Tatjana
authors.initials: T
authors.lastname: Stopar Pintaric
authors.forename: Peter
authors.initials: P
authors.lastname: Veranic
authors.forename: Admir
authors.initials: A
authors.lastname: Hadzic
authors.forename: Manoj
authors.initials: M
authors.lastname: Karmakar
authors.forename: Erika
authors.initials: E
authors.lastname: Cvetko
mesh_terms: D000818:Animals; D005205:Fascia / Q000648:ultrastructure*; D007366:Intercostal Muscles / Q000648:ultrastructure*; D008297:Male; D008854:Microscopy, Electron / Q000379:methods; D010994:Pleura / Q000648:ultrastructure*; D051381:Rats; D017208:Rats, Wistar; D013904:Thoracic Vertebrae / Q000648:ultrastructure*