(A) Diagram of BASC and AT2 co-culture. (B) Representative images of alveolar, bronchiolar and bronchioalveolar organoids after 2 weeks of culture; scale bar = 50 μm. (C) Representative images of alveolar, bronchiolar and bronchioalveolar organoid immunofluorescence staining; scale bar = 50 μm. (D and E) Area of BASC and AT2 colonies. Term hAECs significantly enhanced the size of both BASCs and AT2 in vitro, compared with preterm hAECs. (F and G) Number of BASC and AT2 colonies. Both term and preterm hAECs significantly increased the number of both BASCs and AT2 in vitro, and term hAECs increased the number of BASCs compared with preterm hAECs. (H) The percentage of each type of colony. There is no difference between groups. Statistical significance was determined with one-way ANOVA accompanied by the Bonferroni post-hoc test (*P<0.05, **P<0.01, ***P<0.001, ****P<0.0001).