title: Myofibroblasts in the normal conjunctival surface.
abstract: OBJECTIVE
  To investigate the occurrence of myofibroblasts (MFBs) in the normal conjunctival surface and to evaluate any anatomical and time-related variations.
  
  
  METHODS
  MFBs were screened among healthy individuals (35 eyes) by collecting impression cytology (IC) samples from the bulbar conjunctiva. A cohort of volunteers (12 eyes) was followed for 1 year by taking two to five imprints every month. MFBs were identified by immunohistochemical localization of the MFB marker alpha-smooth-muscle actin (alpha-SMA).
  
  
  RESULTS
  Using a filter imprint technique, MFBs were found consistently in 94% of samples from the conjunctival surface of participating individuals. The overall MFB levels, expressed as percentage of all cells on the filter, were highest in March-May [mean 4.1%, standard deviation (SD) +/- 1.5] and lowest in December-February (mean 1.2%, SD +/- 0.5). The difference was statistically significant [p < 0.0005, Friedman test, one-way repeated measures analysis of variance (anova)]. Moreover, there was a clear divergence of MFB density between the nasal, temporal, superior and inferior bulbar conjunctiva (mean 1.7%, 1.9%, 22% and 9.7%, respectively).
  
  
  CONCLUSIONS
  MFBs, known as a cellular constituent of granulation tissue in wound healing, occur in the normal conjunctival surface, which is a novel finding. Our results also show that MFB level follows a seasonal variation pattern in a temperate climate, increasing in April-September and decreasing in October-March. This variation might reflect a degree of a transient or ongoing state of tissue repair after conjunctival trauma or stress caused by exposure to environmental factors.
authors.affiliation: Department of Ophthalmology, Sahlgrenska University Hospital/Mölndal, Gothenburg, Sweden.
authors.forename: Ximena
authors.initials: X
authors.lastname: Aguilar
authors.forename: David
authors.initials: D
authors.lastname: Hallberg
authors.forename: Karin
authors.initials: K
authors.lastname: Sundelin
authors.forename: Charles
authors.initials: C
authors.lastname: Hanson
authors.forename: Kristina
authors.initials: K
authors.lastname: Stenberg
authors.forename: Mats
authors.initials: M
authors.lastname: Brune
authors.forename: Ulf
authors.initials: U
authors.lastname: Stenevi
mesh_terms: D000199:Actins / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D000368:Aged; D003228:Conjunctiva / Q000166:cytology* / Q000378:metabolism; D005260:Female; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D005500:Follow-Up Studies; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D011123:Polyploidy; D012621:Seasons; D055815:Young Adult
chemical_list: C541116:ACTA2 protein, human; D000199:Actins