title: Quantification and distribution of neovascularization following microinjection of C6 glioma cells in rat brain.
abstract: BACKGROUND
  It has been suggested that the switch to an angiogenic phenotype can separate the development of a tumor into two stages: the prevascular phase and the vascular phase. The purpose of the present work is to demonstrate the existence of an angiogenic switch in a longitudinal study of a brain tumor model during tumor growth by means of microvessel density measurements.
  
  
  METHODS
  The study was performed on 32 rats bearing C6 glioma. At different stages of tumor growth, the histological aspects were described and sections were immunostained for factor VIII-related antigen in order to highlight microvessel endothelial cells. Microvessels were counted at 400 magnification for different areas (central non necrotic area, peripheral area, contralateral grey and white matter area), using image analysis software.
  
  
  RESULTS
  Vessel density was significantly higher at the tumor-brain interface than in the center of the tumor or in the contralateral cortex. The vessel density remains stable in the tumor during the first 3 weeks after cell implantation, after which a clear increase of vessel density can be observed.
  
  
  CONCLUSIONS
  The present study demonstrates the presence of an angiogenic switch which is concomitant with the development of necrosis and pseudopalisading pattern.
authors.affiliation: INSERM U438, Grenoble, France. Michel.Peoch@ujf-grenoble.fr
authors.forename: M
authors.initials: M
authors.lastname: Péoc'h
authors.forename: G
authors.initials: G
authors.lastname: Le Duc
authors.forename: A
authors.initials: A
authors.lastname: Trayaud
authors.forename: R
authors.initials: R
authors.lastname: Farion
authors.forename: J F
authors.initials: JF
authors.lastname: Le Bas
authors.forename: B
authors.initials: B
authors.lastname: Pasquier
authors.forename: C
authors.initials: C
authors.lastname: Rémy
mesh_terms: D000818:Animals; D001932:Brain Neoplasms / Q000098:blood supply* / Q000473:pathology; D005260:Female; D005910:Glioma / Q000098:blood supply* / Q000473:pathology; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic; D051381:Rats; D017208:Rats, Wistar