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Updated: Jul 9, 2026
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Protocol and Guidelines for Point-of-Care Lung Ultrasound in Diagnosing Neonatal Pulmonary Diseases Based on International Expert Consensus
Published on: March 6, 2019
Evidence and structural mechanism for late lung alveolarization
Johannes C Schittny1, Sonja I Mund, Marco Stampanoni
1Institute of Anatomy, University of Bern, Baltzerstrasse 2, Bern, Switzerland. johannes.schittny@ana.unibe.ch
American Journal of Physiology. Lung Cellular and Molecular Physiology
|November 23, 2007
Summary
Lung development continues into young adulthood, with new alveolar septa forming even after microvasculature maturation. This challenges the view that alveolarization stops early, suggesting ongoing lung plasticity.
Area of Science:
- Pulmonary biology
- Developmental biology
- Respiratory medicine
Background:
- Current understanding posits alveolar septa formation ceases post-microvasculature maturation (postnatal days 14-21 in rats).
- This maturation involves reducing alveolar septal capillaries from double- to single-layered networks.
Purpose of the Study:
- To challenge the established view on the cessation of alveolar septa formation.
- To investigate the timeline and mechanisms of alveolar septa development and microvasculature changes in rats.
Main Methods:
- Stereological measurements of new alveolar septa formation.
- Three-dimensional (3-D) visualizations using high-resolution synchrotron radiation X-ray tomographic microscopy.
- Analysis of alveolar capillary networks in developing rat lungs.
Main Results:
- New alveolar septa formation occurs at least until young adulthood (rats, days 4-60).
- Approximately half of newly formed septa originate from mature septa with single-layered capillary networks.
- Local duplication of the capillary network was observed at the base of newly forming septa.
Conclusions:
- Alveologenesis can occur at any time and location within the lung parenchyma, indicating continuous lung development into young adulthood.
- Two distinct phases of developmental alveolarization were identified: phase one (days 4-21) and phase two (day 14 through young adulthood).
- Clinical implications suggest caution when using drugs that affect structural lung development during these phases.
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