title: AngleJ: A new tool for the automated measurement of neurite growth orientation in tissue sections.
abstract: BACKGROUND
  Regeneration of axons is one means to restore function after central nervous system and peripheral nervous system injury. Besides increasing the number of regenerating axons, guidance of axons over long distances into and across a lesion site are important determinants for efficient functional restoration. Quantification of axon growth directions is therefore an important measure for the efficacy of neuroregenerative approaches. While several methods exist to manually or automatically trace neurites in images of neuronal cultures to determine their length, tools to automatically measure the effect of neurite guidance in tissue sections do not exist.
  
  
  METHODS
  Because manual measurements of the orientation of regenerating axons are labor-intensive, time-consuming and unreliable, a plugin called AngleJ for the open source software ImageJ was developed that automatically determines axonal orientation in images of immunohistochemically labeled sections of the spinal cord.
  
  
  RESULTS
  Given user-defined filters and thresholds, the plugin accurately detects neurites in sections of the intact spinal cord white matter and a spinal cord hemisection lesion model and measures the distribution pattern of axonal angles.
  
  
  METHODS
  Values of automatically measured angles strongly correlate with angles obtained by manual measurements in ImageJ (Pearson correlation 0.88-0.97 for white matter and 0.76-0.94 for axons sprouting into a lesion site).
  
  
  CONCLUSIONS
  AngleJ can be used as a fast alternative to manual angle measurement in conjunction with ImageJ and its source code is freely available to the community.
authors.affiliation: Spinal Cord Injury Center, Heidelberg University Hospital, 69118 Heidelberg, Germany.
authors.forename: Manuel Ingo
authors.initials: MI
authors.lastname: Günther
authors.affiliation: Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Günther
authors.affiliation: Spinal Cord Injury Center, Heidelberg University Hospital, 69118 Heidelberg, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Schneiders
authors.affiliation: Spinal Cord Injury Center, Heidelberg University Hospital, 69118 Heidelberg, Germany.
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Rupp
authors.affiliation: Spinal Cord Injury Center, Heidelberg University Hospital, 69118 Heidelberg, Germany. Electronic address: armin.blesch@med.uni-heidelberg.de.
authors.forename: Armin
authors.initials: A
authors.lastname: Blesch
mesh_terms: D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics / Q000378:metabolism; D004195:Disease Models, Animal; D001330:Electronic Data Processing / Q000295:instrumentation* / Q000379:methods*; D005260:Female; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007091:Image Processing, Computer-Assisted; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D009416:Nerve Regeneration / Q000502:physiology; D016501:Neurites / Q000502:physiology*; D055495:Neurogenesis; D009474:Neurons / Q000166:cytology* / Q000187:drug effects; D051381:Rats; D011916:Rats, Inbred F344; D013116:Spinal Cord / Q000166:cytology; D013119:Spinal Cord Injuries / Q000473:pathology / Q000601:surgery; D014162:Transfection
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D049452:Green Fluorescent Proteins
keywords: Angle measurement; Axon growth; Axon guidance; Image analysis; ImageJ; Neurite detection; Regeneration