In A.nidulans, MT polymerization is initiated at sMTOCs and not only from nuclear SPBs. SPA18 directly binds to ApsB at SPBs and sMTOCs, forming an ApsB/SPA18 complex which is required for recruitment of γ-TuRCs. ApsB and SPA18 are targeted to sMTOC by SPA10, to the OP of SPBs by SepK. MztA is a γ-TuRC protein. PcpA is the γ-TuRC receptor at the IP of SPB. SfiA is essential for SPB duplication. All of the findings suggest only the outer plaque of SPB locates at the sMTOC.