Given the anatomic complexity at the bifurcation point of a nerve trunk,enforced suturing between stumps can lead to misdirection of nerve axons,thereby resulting in adverse consequences.We assumed that Y-tube conduits injected with human umbilical cord stem cells could be an effective method to solve such problems,but studies focused on the best type of Y-tube conduit remain controversial.Therefore,the present study evaluated the applicability and efficacy of various types of Y-tube conduits containing human umbilical cord stem cells for treating rat femoral nerve defects on their bifurcation points.At 12 weeks after the bridging surgery that included treatment with different types of Y-tube conduits,there were no differences in quadriceps femoris muscle weight or femoral nerve ultrastructure.However,the Y-tube conduit group with longer branches and a short trunk resulted in a better outcome according to retrograde labeling and electrophysiological analysis.It can be concluded from the study that repairing a mixed nerve defect at its bifurcation point with Y-tube conduits,in particular those with long branches and a short trunk,is effective and results in good outcomes. Given the anatomic complexity at the bifurcation point of a nerve trunk, enforced suturing between stumps can lead to misdirection of nerve axons, thereby resulting in adverse consequences. We assume that Y-tube conduits injected with human umbilical cord stem cells could be an effective method to solve such problems, but studies focused on the best type of Y-tube conduit remain controversial.Therefore, the present study evaluating the applicability and efficacy of various types of Y-tube conduits containing human umbilical cord stem cells for treating rat femoral nerve defects on their bifurcation points. At 12 weeks after the bridging surgery that included treatment with different types of Y-tube conduits, there were no differences in quadriceps femoris muscle weight or femoral nerve ultrastructure. Host, the Y-tube conduit group with longer branches and a short trunk resulted in a better outcome according to retrograde labeling and electrophysiological analysis. It can be concluded from th e study that repairing a mixed nerve defect at its bifurcation point with Y-tube conduits, in particular those with long branches and a short trunk, is effective and results in good outcomes.