title: Arrector pili muscle: evidence of proximal attachment variant in terminal follicles of the scalp.
abstract: BACKGROUND
  There is general agreement that the proximal attachment site of the arrector pili (AP) muscle, via elastic tendons, is the bulge region, where follicular stem cells are situated. A variant of this insertion, in which the AP muscle surrounds the follicle circumference, has been described in human facial vellus hair follicles.
  
  
  OBJECTIVE
  To investigate whether terminal hair follicles of the human scalp may also present this variant of proximal insertion of the AP muscle.
  
  
  METHODS
  Histological and immunohistochemical methods were used.
  
  
  RESULTS
  At the bulge level, bundles of the AP muscle were seen to encircle the entire hair follicle.
  
  
  CONCLUSIONS
  Terminal follicles of the human scalp may also present this variant of proximal insertion of the AP muscle.
authors.affiliation: Federal University of São Paulo, Rua Farme de Amoedo 106, Ipanema, Rio de Janeiro 22420-020, Brazil. baptista@ax.apc.org
authors.forename: Carlos Baptista
authors.initials: CB
authors.lastname: Barcaui
authors.forename: J
authors.initials: J
authors.lastname: Piñeiro-Maceira
authors.forename: M M
authors.initials: MM
authors.lastname: de Avelar Alchorne
mesh_terms: D018859:Hair Follicle / Q000033:anatomy & histology*; D006801:Humans; D007124:Immunoenzyme Techniques; D009130:Muscle, Smooth / Q000033:anatomy & histology*; D012535:Scalp / Q000033:anatomy & histology*