Fecal incontinence and constipation after procedures for anorectal malformations (ARMs) are closely related to the maldevelopment of the striated muscle complex (SMC). Previous studies have demonstrated that myogenic regulatory factors (MRFs) play a significant role in muscle development. Wnt signal pathway is extremely important for MRFs regulation. This study was designed to investigate the spatiotemporal expression pattern of Wnt5a in SMC in ARMs rat embryos. Materials and Methods: Anorectal

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... malformation embryos were induced by eth-ylene thiourea on embryonic day 10 (E10). Expression levels of protein and mRNA of Wnt5a were confirmed by im-munohistochemistry staining, western blot and quantitative real-time PCR (qRT-PCR) between normal rat embryos and embryos with ARMs. Results: Immunostaining revealed that, on embryonic day 17 (E17), the Wnt5a protein was initially expressed in the SMC in normal embryos. With the growth of pregnancy, the positive staining cells gradually increased. The same time-dependent changes of Wnt5a protein were detected in ARMs embryos. Besides, immu-nostaining showed that Wnt5a had a significant increase in normal embryos compared with ARMs embryos. Similarly , in Western blot and qRT-PCR, the higher expression of Wnt5a protein and mRNA were remarkable in normal embryos during the SMC development, relatively. Conclusion: Our study demonstrated that the downregulation of Wnt5a at the time of SMC development might partly be related to the dysplasia of SMC in ARMs.