Hematoxylin and eosin (H&E) staining

Kidney tissues were fixed in 4% (v/v) paraformaldehyde for 48 h at room temperature, then placed in ethanol solution for gradient dehydration (75, 85, 95 and 100%) and made transparent in xylene for 30 min. Finally, the transparent kidney tissues were embedded in paraffin and sliced into 5-µm thick sections. The slices were incubated overnight in an oven at 65°C, then dewaxed in xylene for 30 min and rehydrated in fractionated ethanol series for histological examination. Next, the sections were stained with H&E (Beijing Solarbio Science & Technology Co., Ltd.) according to the standardized H&E staining procedure with Hematoxylin for 10 min and Eosin for 15 sec at room temperature and observed under a bright field using a DP73 microscope (Olympus Corporation; magnification, ×400).