Fig. 4

ER stress induced cell death after exposure to chronic IH. a A small number of apoptotic cells were observed around pulmonary alveoli in the control normoxia group (i) and TUDCA treatment (ii). Significantly increased number of apoptotic alveolar cells were observed in the IH group (iii); however, apoptotic cell counts were lower in the IH+ TUDCA group when compared to the IH group. The inset of each picture is enlarged and displayed on the right. Most of the apoptotic alveolar cells (indicated by arrowheads) were type II alveolar epithelial cells. The pooled data from 4 mice for each group are summarized in b (n = 4). Scale bar: 25 μm. *P < 0.05; **P < 0.01; ns P > 0.05