Title: alveolar period
Long Title: IUPAC Gold Book - alveolar period
DOI: 10.1351/goldbook.16261
Status: current

Definition
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.

Related Terms
- alveoli: https://goldbook.iupac.org//terms/view/10359
- in utero: https://goldbook.iupac.org//terms/view/10862

Source
- PAC, 2016, 88, 713. 'Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)' on page 719 (https://doi.org/10.1515/pac-2015-1202)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/16261/html
- json: https://goldbook.iupac.org/terms/view/16261/json
- xml: https://goldbook.iupac.org/terms/view/16261/xml

Citation: Citation: 'alveolar period' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.16261
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Disclaimer: The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.
Accessed: 2026-07-14T10:45:34+00:00