Definition: "A type of endosome in which regions of the limiting endosomal membrane invaginate to form internal vesicles; membrane proteins that enter the internal vesicles are sequestered from the cytoplasm. In oocytes, multivesicular bodies are abundant on the dorsal side of the NF stage 7 (64-cell) embryos (as a result of cortical rotation) are are frequently surrounded by clouds of smaller, darker cytoplasmic membranes that may represent cytoplasmic determinants."