English: sRNA is produced by Dicing of larger dsRNA molecules in the transmitting cell. On the left, non-vesicular dsRNA and sRNA are secreted by unknown mechanisms. Uptake of this RNA is depicted in a manner that resembles SID-1/SID-2 mediated uptake [39]. DsRNA is bound by a receptor and internalized, after which it is taken up into the cytosol by a transmembrane channel, such as SID-1. In the middle, transfer of sRNAs through MVB-mediated exosomes is depicted. A model for loading of sRNA into intraluminal vesicles of MVBs (MVB) is suggested [49]. These vesicles are released in the intercellular space as exosomes after fusion of MVBs with the plasma membrane (PM). Exosomes are taken up by endocytosis into the receiving cell. It is unknown how sRNA is released into the cytosol, but one could envisage a fusogenic protein (F) to be involved, which facilitates fusion of the endosomal and exosomal membranes. On the right, transfer of sRNA in shedding vesicles (SV), which are generated directly from the PM, is depicted. How RNA is loaded into SV is unknown. The recipient cell takes up the sRNA after fusion of the SV with the PM in a process that requires fusogenic proteins. SVs might be taken up in an endocytosis-dependent manner and exosomes might be taken up in a membrane fusion event. In the cytosol of the recipient cell, the sRNA is recognized by the RNAi machinery and triggers gene silencing, either through post-transcriptional gene silencing (PTGS) or transcriptional gene silencing (TGS). During PTGS, amplification of the sRNA signal is provided by RNA-dependent RNA polymerases (RdRP), which give rise to secondary sRNAs that can target the same or other transcripts.