We discovered that mouse oocytes contain novel non-membrane-bound organelles which we named EndoLysosomal Vesicular Assemblies (ELVAs). ELVAs contain endolysosomal and autophagy vesicles as well as Proteasomes held together by a matrix protein. To discover the matrix protein holding ELVAs together we subjected mouse oocyte with fluorescently labelled ELVAs to mechanical lysis followed by Fluorescence-Activated Particle Sorting to enrich for ELVAs. Enriched ELVAs were then subjected to proteomics.