Our observations of living spermatocytes showed that the accumulation of a myosin subunit at the prospective CF region could be divided into two successive steps: recruitment along the cell K-Ras(G12C) inhibitor 9 cortex and accumulation to the equatorial cortex region. Two other components, F-actin and anillin, abruptly appeared in a ring on the restricted cortex region where the peripheral MTs made contact. In both Drosophila larval neuroblasts and embryonic cells in Caenorhabditis elegans, it was reported that myosin accumulation in the CF region occurs in two steps; the first involves recruitment of the myosin subunit to a wide region along the cortex,, and the second involves restricting its wide distribution in the equatorial region. Uehara and coauthors also described the two-step accumulation of myosin in Drosophila S2 cells. In contrast, Giansanti and Fuller suggested that spermatocytes appear to skip the first step of myosin accumulation. However, our analysis in the presence of colchicine indicated that myosin accumulation at the CF site was divided into two steps; the first step was independent of MTs, and the next step was dependent on MT structures. As these two successive steps may proceed continuously under normal conditions, it may be difficult to recognize the processes as separate phases without careful observation of living cells. Furthermore, it has also been reported that the initial recruitment is performed dependent on Rho during early anaphase of S2 cells. However, we observed myosin recruitment along the cell cortex in rho1-depleted spermatocytes, although subsequent accumulation of the cortical myosin was entirely inhibited. As we did not succeed in Clozapine detecting the accumulation of GFP-Rho1 at the CF site, its involvement in myosin recruitment in this cell type should be interpreted with caution. In the second step, the initial distribution of myosin is subsequently narrowed to the equatorial cortex zone, depending on CS MTs. A previous study demonstrated that peripheral MTs from opposite spindle poles meet at the mid-zone and make contact with the cortex in spermatocytes.