title: Ultrastructural analysis on lumbar disc herniation using surgical specimens: role of neovascularization and macrophages in hernias.
abstract: METHODS
  The mechanisms responsible for the spontaneous regression of lumbar disc herniation (LDH) were studied by examining herniated tissue collected at operation from patients with LDH.
  
  
  OBJECTIVE
  The aim of the present study was to investigate the role of neovascularization and macrophages in hernias when spontaneous regression of LDH occurred.
  
  
  BACKGROUND
  Spontaneous regression of LDHs has already been demonstrated by diagnostic imaging with tools such as magnetic resonance imaging. However, there have been few studies on the mechanisms of spontaneous regression based on pathologic examination of herniated tissue. In particular, there has been no detailed work on the role of macrophages, which are thought to be closely associated with spontaneous regression.
  
  
  METHODS
  The magnetic resonance imaging and operative findings of 73 patients who underwent surgery were investigated, and specimens collected during surgery were examined by light and transmission electron microscopy.
  
  
  RESULTS
  Capillaries that invade the hernia and macrophages derived from monocytes migrating out of these capillaries are considered to be important factors in the regression of the herniated disc. Macrophages contain lysosomes filled with collagen-degrading enzymes that break down substances after phagocytosis, whereas primary lysosomes are secreted by these cells and break down intercellular substances such as collagen. Both of these mechanisms are closely involved in the regression of herniation.
  
  
  CONCLUSIONS
  The inflammatory response that occurs around hernia tissue in the epidural space is believed to play an important role in herniated disc resorption, although it may also have a harmful effect on the adjacent nerve root. Therefore, control of the inflammatory reaction is an important challenge when treating patients with disc herniation.
authors.affiliation: Department of Orthopaedics and Rehabilitation Medicine, The University of Fukui, Shimoaizuki 23, Matsuoka, Fukui, Japan. kshigeru@u-fukui.ac.jp
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Adam
authors.initials: A
authors.lastname: Meir
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Kokubo
authors.forename: Kenzo
authors.initials: K
authors.lastname: Uchida
authors.forename: Kenichi
authors.initials: K
authors.lastname: Takeno
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Miyazaki
authors.forename: Takafumi
authors.initials: T
authors.lastname: Yayama
authors.forename: Masafumi
authors.initials: M
authors.lastname: Kubota
authors.forename: Eiki
authors.initials: E
authors.lastname: Nomura
authors.forename: Erisa
authors.initials: E
authors.lastname: Mwaka
authors.forename: Hisatoshi
authors.initials: H
authors.lastname: Baba