Figure 4 A: HE staining of the middle ear mucosa of the experimental group under 200x microscope;B: The middle ear mucosa of the experimental group was stained by HE under 400 times microscope.C: The middle ear mucosa of the control group was stained with HE under 200x microscope.D: The middle ear mucosa of the control group was stained by HE under 400 times microscope.