Organization of microtubules in mouse RPE cells. (A) STED super-resolution microscopy image of a section of the RPE from an albino mouse, labeled with α-tubulin antibodies. Arrowheads indicate vertical microtubules. Horizontal microtubules are evident, predominantly near the apical margin of the cell body (arrows). (B) Single-plane confocal microscopy images of RPE cells in whole-mount preparations, showing the organization of the microtubules (immunolabeled with anti–α-tubulin; green) at different apical-basal locations. (C) EB1 immunolocalization (red) in a section of an albino mouse RPE, indicating localization of the plus ends of the microtubules mainly in the basal region. Ch, choroid. (D) Diagram of the indicated organization and polarity of microtubules in RPE cells. Bars, 10 µm.