Scanning Electron Microscopy Analysis of Microvilli

For SEM analysis cells were cultivated in cover glasses (WHB-12-CS, Shanghai Wohong Biotechnology, China) within Transwell. Firstly, cells were fixed in 2.5% glutaraldehyde in PBS (0.1 M, pH 7.0) overnight and then were postfixed with 1% OsO₄ in PBS for 1.5-h. In the following cell samples were dehydrated in a graded series of ethanol (30, 50, 70, 80, 90, and 95%) for about 15-min at each step followed by dehydration twice in alcohol (100%) for 20-min. Between the treatment of different solutions cell samples were washed three times in PBS for 15-min per time. SEM analysis of the microvilli on the cell surface was performed by ultra-high resolution scanning electron microscope (SU8010, Hitachi, Japan) in Analysis Center of Agrobiology and Environmental Sciences, Zhejiang University (China).