The histological observation of polypropylene (H&E stain, ). (a) 1 week after implantation. The white area represented polypropylene. There was infiltration of a small number of neutrophils and lymphocytes. The multinucleated giant cells were observed around the polypropylene, and the epithelial cells were not observed. (b) At 1 month, the neutrophils, lymphocytes, and multinucleated giant cells were decreased, while fibroblasts were increased and de novo blood vessels were observed. (c, d, e) At 3, 8, and 12 months after implantation, there was no obvious inflammatory infiltration.