Acetylcholinesterase in cat megakaryocyte. Evidence for extracellular secretion

Cytochemical localization of acetylcholinesterase (AchE E.C.3.1.1.7) was studied in cat bone marrow. The reaction product precipitate was present only in megakaryocytes, and all other marrow cells were AchE-negative. Moderate electron dense AchE reaction product was found in basophilic megakaryocytes in the nuclear membrane, endoplasmic reticulum, Golgi complex, and demarcation membrane system (DMS). In granular and thrombocytogenic stages the intense AchE reaction product was present in all cytoplasmic membranes. The Golgi-derived AchE-positive granules were found to fuse with DMS and their contents were discharged into the extracellular compartment.