Exocytosis of intact lysosomes from skeletal muscle after chloroquine treatment

Following short-term chloroquine treatment (25 mg/kg daily for 7 days), intact myeloid bodies were extruded from the anterior latissimus dorsi (ALD) muscle of the chicken. These myeloid bodies demonstrated acid phosphatase activity both within the cell and after extrusion into the extracellular space. Tannic acid staining confirmed that the plasma membrane remained intact and the “extracellular lysosomes” observed had not resulted from fixation damage. Lysosome extrusion following overloading in skeletal muscle and the fate of the lysosomal contents after extrusion are discussed.