Core actin bundles contain ∼100 hexagonally packed actin filaments. (A) TEM of ultrathin tissue section depicting tuft cell apical protrusions imaged en face (scalebar = 200 nm) and enterocyte masked in blue, zoom inset on right (scalebar = 100 nm). The yellow arrow points to an instance of actin dislocation. (B) Frequency distribution of the number of filaments per bundle (n = 22 bundles over 3 tuft cells. Median values per tuft cell: 108, 102, and 100). (C) Frequency distribution showing the diameter of core actin bundles in tuft cell apical protrusions (n = 57 bundles over 3 tuft cells. Median values per tuft cell: 104.4, 108.6, and 103.5 nm). (D) TEM of tissue section tuft cell apical protrusions imaged en face. Map of evenly spaced actin filaments (magenta), Fast Fourier transform (FFT) (top right), bandpass filter (bottom right) (scalebar = 100 nm). (E) Frequency distribution of the angle between nearest neighbor filaments within a 12-nm radius (n = 22 bundles over 3 tuft cells. Median values per tuft cell: 56.7°, 62.6°, and 64.7°). (F) Frequency distribution of the distance between neighboring filaments identified in E (n = 22 bundles over 3 tuft cells. Median values per tuft cell: 8.8, 9, 9.1 nm). (G) Map of hexagonally packed filaments on five different protrusions taken from D. FFT (top right), bandpass filter (bottom right) (scalebar raw image = 20 nm, FFT and filter scalebar = 20 nm⁻¹). (H) TEM of tissue section depicting a mostly lateral view of a tuft cell with enterocytes masked in blue. Core actin bundles are outlined in green (scalebar = 1 µm). Zoom insets on bottom show the base of the rootlets (left) and core bundles near the apical surface (right) (scalebars = 200 nm).