The Number of Alveoli in the Terminal Respiratory Unit of Man During Late Intrauterine Life and Childhood

Abstract

A systematic and statistical study has been carried out on the lungs of children dying during the later part of gestation and through childhood up to 12 years of age. An estimate has been made of the number of alveoli in the terminal respiratory unit and this shows a rapid increase during the first year after birth and a steady increase throughout childhood, there being apparently a nine-fold increase in the alveoli after birth. If consideration is also given to the increased proliferation of the respiratory tree after birth, there is the possibility of a thousand-fold increase in the number of alveoli between birth and puberty.