PAS, AB, and AB-PAS staining

After ALI culture, 1 ml Carnoy's solution was added into the the upper chamber of the whole Transwell inserts, and the upper chamber was fixed for 10 min, and then washed with PBS for three times. Afterwards, the upper chamber was stained with Alcian Blue staining solution (pH 2.5) for 10 min, followed by rinsing in distilled water three times for each time 1-2min. Then, the membrane of the upper chamber was cut off gently and put on the glass slide for visualizing under the microscope.