Centrioles are essential for the formation of cilia and flagella. They also form 
the core of the centrosome, which organizes microtubule arrays important for 
cell shape, polarity, motility and division. Here, we have used super-resolution 
3D-structured illumination microscopy to analyse the spatial relationship of 18 
centriole and pericentriolar matrix (PCM) components of human centrosomes at 
different cell cycle stages. During mitosis, PCM proteins formed extended 
networks with interspersed γ-Tubulin. During interphase, most proteins were 
arranged at specific distances from the walls of centrioles, resulting in ring 
staining, often with discernible density masses. Through use of site-specific 
antibodies, we found the C-terminus of Cep152 to be closer to centrioles than 
the N-terminus, illustrating the power of 3D-SIM to study protein disposition. 
Appendage proteins showed rings with multiple density masses, and the number of 
these masses was strongly reduced during mitosis. At the proximal end of 
centrioles, Sas-6 formed a dot at the site of daughter centriole assembly, 
consistent with its role in cartwheel formation. Plk4 and STIL co-localized with 
Sas-6, but Cep135 was associated mostly with mother centrioles. Remarkably, Plk4 
formed a dot on the surface of the mother centriole before Sas-6 staining became 
detectable, indicating that Plk4 constitutes an early marker for the site of 
nascent centriole formation. Our study provides novel insights into the 
architecture of human centrosomes and illustrates the power of super-resolution 
microscopy in revealing the relative localization of centriole and PCM proteins 
in unprecedented detail.