From postsynaptic granule cells at the time of synapse formation. The addition of recombinant Wnt7a is sufficient to induce changes in growth-cone morphology in mossy fiber explant culture, whereas blocking endogenous Wnts inhibits the maturation process (Hall et al. 2000). In Wnt7a knockout mice, rosette formation is delayed, which suggests that Wnt7a is an important player in this process and th