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Development of the bronchial epithelial reticular basement membrane: relationship to epithelial height and age
  1. Lemonia Tsartsali1,
  2. Alison A Hislop2,
  3. Karen McKay3,
  4. Alan L James4,
  5. John Elliot4,
  6. Jie Zhu5,
  7. Mark Rosenthal1,
  8. Donald N Payne6,
  9. Peter K Jeffery5,
  10. Andrew Bush1,
  11. Sejal Saglani1
  1. 1Respiratory Paediatrics, Royal Brompton Hospital, Imperial College London, London, UK
  2. 2Developmental Vascular Biology, University College London, Institute of Child Health, London, UK
  3. 3Respiratory Medicine, Children's Hospital at Westmead, The University of Sydney, New South Wales, Australia
  4. 4West Australian Sleep Disorders Research Institute, Perth, Western Australia
  5. 5Lung Pathology, Department of Gene Therapy, Imperial College London, London, UK
  6. 6School of Paediatrics and Child Health, The University of Western Australia, Australia
  1. Correspondence to Dr Sejal Saglani, Imperial College London, National Heart & Lung Institute, 374 Sir Alexander Fleming Building, Exhibition Road, London SW7 2AZ, UK; s.saglani{at}


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.

  • Epithelial mesenchymal trophic unit
  • remodelling
  • asthma
  • development
  • reticular basement membrane
  • airway epithelium
  • histology/cytology
  • paediatric lung disaese

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  • Funding The British Paediatric Respiratory Society, Asthma UK, The Wellcome Trust, UK. SS is funded by an Intermediate Clinical Fellowship from the Wellcome Trust. AJ is supported by a National Health and Medical Research Council of Australia Practitioner Fellowship.

  • Competing interests None.

  • Ethics approval This study was conducted with the approval of the local ethics committees at each centre from which tissue was obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed.