title: Development of the bronchial epithelial reticular basement membrane: relationship to epithelial height and age.
abstract: BACKGROUND
  The bronchial epithelium and underlying reticular basement membrane (RBM) have a close spatial and functional inter-relationship and are considered an epithelial-mesenchymal trophic unit (EMTU). An understanding of RBM development is critical to understanding the extent and time of appearance of its abnormal thickening that is characteristic of asthma.
  
  
  METHODS
  RBM thickness and epithelial height were determined in histological sections of cartilaginous bronchi obtained postmortem from 47 preterm babies and infants (median age 40 weeks gestation (22 weeks gestation-8 months)), 40 children (2 years (1 month-17 years)) and 23 adults (44 (17-90) years) who had died from non-respiratory causes, and had no history of asthma.
  
  
  RESULTS
  The RBM was visible by light microscopy at 30 weeks gestation. RBM thickness increased in successive age groups in childhood; in infants (r=0.63, p<0.001) and in children between 1 month and 17 years (r=0.82, p<0.001). After 18 years, RBM thickness decreased with increasing age (r=-0.42, p<0.05). Epithelial height showed a similar relationship with age, a positive relationship from preterm to 17 years (r=0.50, p<0.001) and a negative relationship in adulthood (r=-0.84, p<0.0001). There was a direct relationship between epithelial height and RBM thickness (r=0.6, p<0.001).
  
  
  CONCLUSIONS
  The RBM in these subjects was microscopically identifiable by 30 weeks gestation. It thickened during childhood and adolescence. In adults, there was either no relationship with age, or a slow reduction in thickness in older age. Developmental changes of RBM thickness were accompanied by similar changes in epithelial height, supporting the close relationship between RBM and epithelium within the EMTU.
authors.affiliation: Respiratory Paediatrics, Royal Brompton Hospital, Imperial College London, London, UK.
authors.forename: Lemonia
authors.initials: L
authors.lastname: Tsartsali
authors.forename: Alison A
authors.initials: AA
authors.lastname: Hislop
authors.forename: Karen
authors.initials: K
authors.lastname: McKay
authors.forename: Alan L
authors.initials: AL
authors.lastname: James
authors.forename: John
authors.initials: J
authors.lastname: Elliot
authors.forename: Jie
authors.initials: J
authors.lastname: Zhu
authors.forename: Mark
authors.initials: M
authors.lastname: Rosenthal
authors.forename: Donald N
authors.initials: DN
authors.lastname: Payne
authors.forename: Peter K
authors.initials: PK
authors.lastname: Jeffery
authors.forename: Andrew
authors.initials: A
authors.lastname: Bush
authors.forename: Sejal
authors.initials: S
authors.lastname: Saglani
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology; D001485:Basement Membrane / Q000033:anatomy & histology / Q000254:growth & development; D001827:Body Height / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D001980:Bronchi / Q000033:anatomy & histology / Q000254:growth & development*; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D008875:Middle Aged; D020545:Respiratory Mucosa / Q000033:anatomy & histology / Q000254:growth & development*; D012727:Sex Characteristics; D055815:Young Adult