alveolar period

synonym: alveolar phase
https://doi.org/10.1351/goldbook.16261
Phase in lung development beginning in utero (about \(\pu{32}\) to \(\pu{36}\) weeks in the human fetus) and lasting until about eight years of age.
Note: In this phase, the terminal alveolar saccules subdivide several more times, giving rise to the mature alveoli.
Source:
PAC, 2016, 88, 713. (Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)) on page 719 [Terms] [Paper]