title: The normal growth of the tracheal wall in human foetuses.
abstract: BACKGROUND
  Tracheal wall thickness is a substantial indicator in various pathological changes. The present study was performed to compile normative data and formulae for the tracheal wall thickness and volume at varying gestational age.
  
  
  METHODS
  Using anatomical dissection, digital image analysis and statistics a range of the wall thickness, proximal internal-to-external cross-sectional area ratio, and wall volume for the trachea in 73 spontaneously aborted human fetuses aged 14-25 weeks was examined.
  
  
  RESULTS
  No significant male-female differences were found. The values of tracheal wall thickness ranged from 0.36 ±0.01 mm for the 14-week group to 1.23 ±0.17 mm for the 25-week group of gestation, according to the linear function y = -0.823 + 0.083 × age ± 0.087. The tracheal lumen rate, expressed as the proximal internal-to-external cross-sectional area ratio, decreased from 42.61 ±1.11% to 26.78 ±4.95%, according to the function y = 62.239 - 1.487 × age ±3.119. The tracheal wall volume rose from 16.28 ±4.18 mm(3) in fetuses aged 14 weeks to 269.22 ±29.26 mm(3) in fetuses aged 25 weeks, according to the quintic function y = 0.000052 × age(4.894).
  
  
  CONCLUSIONS
  The tracheal wall parameters show no sexual dimorphism. The tracheal wall grows linearly in its length, and according to a quintic function in its volume. A relative decrease in the tracheal lumen at the expense of an increase in both the wall thickness and wall volume of the trachea is found during gestation.
authors.affiliation: Department of Normal Anatomy, Ludwik Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Torun, Poland.
authors.forename: Michał
authors.initials: M
authors.lastname: Szpinda
authors.forename: Marcin
authors.initials: M
authors.lastname: Daroszewski
authors.forename: Anna
authors.initials: A
authors.lastname: Szpinda
authors.forename: Alina
authors.initials: A
authors.lastname: Woźniak
authors.forename: Celestyna
authors.initials: C
authors.lastname: Mila-Kierzenkowska
authors.forename: Piotr
authors.initials: P
authors.lastname: Flisiński
authors.forename: Marcin
authors.initials: M
authors.lastname: Wiśniewski
keywords: regression analysis; trachea; tracheal lumen rate; wall thickness; wall volume