Lets feed the preterm lung [editorial]

The lung is generally viewed as a static structure once growth has occurred. Its size or ability to regenerate becomes interesting with disease or physiologic stresses. The general teaching is that the adult human lung septates beginning at about 32-36 weeks of gestation to form alveoli and this process continues until the child is several years of age. Subsequent growth is in lung size with a constant number of about 500 million alveoli until about 20 years of age. Alveolar number and lung elasticity then decrease progressively with age. Alveolar loss by destruction in emphysema appears to be an irreversible process. Yet lung growth and alveolarization can occur even in the mature lung. Lung resection in young animals results in prompt growth and expansion of the gas surface area in the remaining lung. More directly relevant to the article on nutritional effects on the developing lung published by Mataloun et al. in the Journal are studies of the effects of starvation on adult lungs. Humans who were starved to death in the Warsaw Ghetto during World War II were noted to have emphysema at autopsy. Young women with anorexia nervosa have emphysema as assessed by CT scans. These observations indicate that changes in lung structure do occur in the adult lung and that nutritional status is a modulator of lung structure. (excerpt)