Fig. 2

TEM–EDX elemental analysis of BG structures. A Representative TEM images of CD9-immunolabeled EVs from BG tissues, from the three RM groups. The black spots on the structures correspond to 6-nm-gold-nanoparticles-labeled goat anti-mouse secondary antibody. B Total of 25 TEM images were analyzed for size and counted for the immunogold label per vesicle and the means were reported per group. Error bar represent standard error of the mean. The number above the bars represent the number of vesicles analyzed per group. C Representative images of MC from BG tissues. Seen are dense, sharp-edged and membraneless structures of primary particle size of ~ 10–20 nm that aggregate into large structures up to ~ 500 nm. D Corresponding EDX spectra of the MC structures revealing presence of SPONCH (Sulphur, S; Phosphorus, P; Oxygen, O; Nitrogen, N; Carbon, C; and H, Hydrogen) elements, as a signature of biomolecules. Despite the strong signal of copper, Cu and chromium, Cr which constitute the main material of the specimen holder, and the fact that H is beyond the EDX detection limit and C may also be a specimen artifact, persistent traces of SPON, sulfur, phosphorus, oxygen, and nitrogen, were detected, supporting a ribonucleo-proteinaceous nature of the MC structures