ABSTRACT
<p><b>OBJECTIVE</b>To explore the patterns of Cx43 and Pax3 protein expressions in the small intestinal muscular layers of human embryo during early development.</p><p><b>METHODS</b>Immunohistochemistry with SABC method was employed to examine the expression of Cx43 and Pax3 proteins in the muscular layers of the small intestine in early human embryos in the second to fourth months of gestation.</p><p><b>RESULTS</b>In the second month of gestation, the muscle layer of the small intestine was negative for Cx43 and Pax3 protein expressions. In the third month, Cx43 and Pax3 expressions were negative in the inner circular muscle layer, but some positive cells were found in the longitudinal muscle layer and the myenteric plexus. In the fourth month, positive expression of Cx43 and Pax3 proteins were seen in the entire muscle layer.</p><p><b>CONCLUSION</b>Cx43 and Pax3 proteins are closely related to the growth and development of the cells and tissues in the small intestinal muscle layer in human embryos.</p>
