 Along with the role of Wnt genes in patterning the anteroposterior axis through gradient polarization, "Wnt8b" is expressed within the ZLI itself and may help guide dorsal movement of "Shh" expression.The Wnt polarization gradient has been linked to induction of ZLI-patterning genes "IRX3" and "SIX3", which border the ZLI posteriorly and anteriorly, respectively.However, these genes have been shown to be non-essential for ZLI formation in zebrafish and have been reevaluated in other models.