The Centrosome Duplication Cycle. The centrosome consists of mother and daughter centrioles (green), that are interconnected by an intercentriolar linkage (red) and are embedded in the pericentriolar material (grey) which anchors the microtubules. The mother centriole can be distinguished by the presence of appendages (black lines). (a) During G1, cells lose their orthogonal arrangement. (b) As G1/S, a procentriole (blue) forms perpendicular to each centriole. (c) During S phase, the new centrioles elongate. (d) At G2, the two newly formed centriole pairs disconnect, and (e) by G2/M, the PCM is also divided between the centrioles. (f) At the end of the cycle, the daughter centrioles acquire appendages and behave as a mother centriole during the subsequent cycle.