cytosome noun2 •The cytoplasm within a cell; the cell outside of the nucleus.The fundamental component of the protozoan body is the protoplasm which is without exception differentiated into the nucleus and the cytosome. — 1946 •A type of cellular organelle which is enclosed by a membrane.Moreover, calcium is concentrated in cytosomes, specific membrane-coated vesicles, which are also known as 'tannin vesicles'. — 1994 formscytosomes