Ds fi1 eclipse

Cardiac sections were fixed in 4% paraformaldehyde, then embedded in paraffin. Sections of 5‐μm thickness were stained with hematoxylin and eosin to evaluate morphology and cellular dimensions. Photomicrographs were obtained by light microscopy (DS‐Fi1‐Eclipse; Nikon, Tokyo, Japan). Myocardial collagen was stained with Masson’s trichrome. Photomicrographs were analyzed in a blinded manner. Photographs of left ventricular sections cut from the posterior inferior septal of each heart were used for morphometric analysis. Changes in myocardial interstitial collagen were observed by using a microscopy imaging system (DS‐Fi1‐Eclipse; Nikon). MF was quantified by measuring the blue fibrotic area. Collagen volume fraction refers to the ratio of the area of collagen relative to the total area of the image. Ten fields at high magnification (×400) were randomly taken and areas of collagen were calculated.

The proliferative activity of cells was determined by using Ki‐67 antibody (1:500 dilution; Servicebio Technology Co, Ltd, Wuhan, China). Each slide was analyzed by confocal microscopy (DS‐Fi1‐Eclipse; Nikon). The total number of Ki‐67⁺ cells and total nuclei was counted from each image. Cells with brown staining were defined as Ki‐67⁺. The proliferation index was determined by dividing the number of Ki‐67⁺ nuclei by the total number of sampled nuclei. Ten fields at high magnification (×400) were randomly taken from every section.