Extended Data Fig. 3: Choroid plexus aposomes.
From: Choroid plexus apocrine secretion shapes CSF proteome during mouse brain development
(A) Intensity of FOS immunofluorescence in E12.5 ChP, N = 8 embryos from 4 litters/condition. (B) Apocrine structures visualized by, from left to right, SEM, H&E stain, and IHC. (C) TEM image depicting an E16.5 ChP epithelial cell with an aposome protruding immediately adjacent to cilia. (D) SEM image depicting an E16.5 ChP epithelial cell with a collapsed, likely post-secretion aposome protruding immediately adjacent to cilia. (E) SEM image depicting an E16.5 epithelial cell with an emerging aposome protruding immediately adjacent to cilia. (F) Representative confocal images of control (top) and apocrine (bottom) LV ChP showing the apical depressions, unstained by Ezrin, from which aposomes arise. (G) Expansion microscopy image depicting two E16.5 ChP epithelial cells, each with aposomes supported by a network of microtubules. (H) Quantification of size of aposomes at E16.5, N = 30 mice from 6 litters. (I) SEM of adult LV ChP after control (saline) or WAY-161503 injection. Aposomes quantified in (J). (K) Two representative silver stains of E16.5 CSF 30 min following maternal saline (control, left) or WAY-161503 (right). Red arrows indicate proteins whose concentration appeared visually to differ between conditions. (L) Expansion microscopy image depicting ChP LV epithelial cells, one with an aposome containing mitochondria (Citrate Synthase antibody). (M) Quantification of LV ChP aposomes at baseline, 30 min after WAY-161503 injection, 24 h after WAY-161503 injection, or after 2 injections of WAY-161503 at a 24 h interval. Data Presentation: All data presented as mean ± SEM. Scale bars 5 µm unless otherwise noted. P values from two-tailed t-test for (A) and (J), and from one-way ANOVA with Tukey correction for (M).
