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. 2008 Jun 27;39(6):717–729. doi: 10.1165/rcmb.2008-0052OC

Figure 5.

Figure 5.

Analysis of apoptosis by TUNEL labeling. Top: TUNEL labeling. (A–D) Representative TUNEL assays of normoxic and hyperoxic lungs at P7 (left). (A) Normoxic wild-type lung. (B) Normoxic lpr lung. (C) Hyperoxic wild-type lung. (D) Hyperoxic lpr lung. Rare TUNEL-positive cells are noted in alveolar septa of normoxic lungs. TUNEL activity is markedly higher in hyperoxic wild-type and lpr lungs. Note the presence of TUNEL-positive pyknotic nuclear fragments, characteristic of apoptosis (arrows). Omission of transferase enzyme abolished all FITC labeling (not shown). (TUNEL-FITC labeling; original magnification: ×400). Right: apoptotic index (AI, number of TUNEL-positive nuclei per high power field). Values represent mean AI ± SD. *P < 0.01 versus corresponding normoxic animals. Bottom: TUNEL labeling combined with anti–SP-C immunohistochemistry. (A–D) Murine lungs at P7. (A) Normoxic wild-type lung. (B) Normoxic lpr lung. (C) Hyperoxic wild-type lung. (D) Hyperoxic lpr lung. TUNEL-positive cells in A and B represent SP-C–negative apoptotic interstitial cells. Arrows in C and D indicate apoptotic SP-C–positive alveolar epithelial type II cells. Omission of transferase enzyme and anti–SP-C antibody abolished all staining (not shown). (TUNEL-FITC labeling and cy-3–labeled anti–SP-C immunofluorescence; original magnification: ×400). Right: type II cell apoptotic index. Values represent mean AI ± SD of SP-C–positive cells, expressed as a percentage. *P < 0.01 versus corresponding normoxic animals.