Centriole length within a population of cycling cells is variable. (A) Examples of centrioles and one primary cilium after 4.2-fold expansion and imaging by conventional widefield microscope using 60× lens. Acetylated tubulin labels centriole MTs and ciliary axoneme. Cep164 is a component of centriole distal appendages present on older mother centriole. ARL13B is a ciliary membrane-associated protein. (B) Quantification of the length of mother centrioles in G1 and S phase. (C) The analysis of mother centriole length in specific phases of the cell cycle. Left: Older and younger mother centrioles plotted separately. Right: Older and younger mother centrioles plotted together. (D) Centrioles from electron micrographs were divided into proximal (dark gray) and distal portions (light gray) at the base of subdistal appendages. The length of these portions was measured and plotted for each centriole. Centrioles were plotted from the longest to the shortest. A linear regression trendline, a regression equation, and a correlation coefficient R² are marked. (E) Examples of centrioles of variable length from HeLa and RPE-1 cells. MC, mother centriole; PC, procentriole. Scale bars, 20 (large) and 2 µm in A; 0.4 µm in E.