The morphometric analysis and side-averaging of Golgi ministacks. (A–D) The axial size of the ministack is approximately conserved, while lateral sizes of ministack cisternae vary in direct proportion. HeLa cells expressing GalT-mCherry were nocodazole-treated and immunostained for GM130 and giantin. Ministacks were subsequently imaged and subjected to morphometric analysis. In A and B, the axial distance from GM130 to GalT-mCherry (which is also the axial size of the ministack; A) or giantin (B) against the lateral size of giantin is plotted. In C and D, the lateral size of GM130 (C) or lateral width of giantin punctum (D) against the lateral size of giantin is plotted. Numbers adjacent to the x and y axis are mean ± SEM values of variables corresponding to the x and y axis, respectively. n, the number of ministacks analyzed. (E) Schematic diagram illustrating the morphometric changes of Golgi ministacks: the axial sizes are conserved while the lateral ones vary proportionally. The two yellow segments schematically represent the distribution of a rim marker. (F) Schematic diagram showing the method of side-averaging. The two blue ovals represent the giantin double-punctum. (x_c, y_c) is the fluorescence center of giantin. (x₁, y₁) and (x₂, y₂) are fluorescence centers of the left and right giantin punctum, respectively. Intensity norm., intensity normalization. (G) An example of side-averaging. HeLa cells were processed as in F. 20 side-view images of giantin were aligned and normalized, and the resulting side-averaged image is shown at the right. Scale bar, 200 nm.