Microvascular maturation of the septal capillary layers takes place in parallel to alveolarization in human lungs

Abstract

Newly formed alveolar septa contain a double-layered capillary network. To optimize gas exchange, the two layers fuse to a single-layered capillary network during microvascular maturation. Because its timing is unknow in humans, microvascular maturation was stereologically estimated throughout postnatal human lung development. It is shown that maturation of the microvascular and alveolar septa takes place in parallel to alveolarization. At an age of 2–3 yr three-quarters of the septa are mature.