Figure 3. Formation of membrane vesicles by osmotic lysis involves membrane rupture and resealing (i.e., the membrane has the properties of a phospholipid bilayer): Top. Addition of colloidal gold (visible in the electron microscope) to spheroplasts reveals gold particles outside, none within. Middle. Same with membrane vesicles. Bottom. Osmotic lysis of spheroplasts in the presence of colloidal gold leads to vesicles with colloidal gold trapped inside. Therefore, release of intracellular contents during lysis involves rupture of the plasma membrane and resealing.
During lysis, the intracellular space equilibrates with the external medium. Thus, in addition to emptying the cell of its soluble contents, during lysis, large molecule such as enzymes or antibodies can be introduced into the intravesicular space.