The paper describes the isolation of synaptosomes, which are discrete particles derived from presynaptic nerve endings in brain tissue. These particles retain the structural features of the nerve endings and are separated using differential and density-gradient centrifugation. Synaptosomes contain acetylcholine, choline acetyltransferase, hydroxytryptamine, and noradrenaline, suggesting that these substances are localized within synaptosomes derived from cholinergic and other neurons. Electron microscopy reveals that synaptosomes consist of thin-walled bags containing synaptic vesicles, mitochondria, and cytoplasm. Synaptic vesicles are classified into three types: hollow, dense-cored, and compound. These vesicles are proposed as the binding sites for neurotransmitters within the nerve endings. The study also details the disruption of synaptosomes to isolate synaptic vesicles, mitochondria, and other components. Water suspension was used to release vesicles, and a density-gradient procedure was employed to separate them from membrane fragments and other structures. The results show that acetylcholine is distributed bimodally in the density gradient, with some in synaptic vesicles and some in incompletely disrupted synaptosomes. Lactate dehydrogenase, a soluble cytoplasmic marker, was mainly recovered in the soluble-cytoplasmic fraction, while succinate dehydrogenase, a mitochondrial marker, was mainly recovered in the mitochondrial fraction. Cholinesterase was found in microsomal and large-membrane fractions. The study also compares the results with those of other researchers, noting that some preparations may be heterogeneous and contaminated with membrane fragments. The authors conclude that synaptosomes are a homogeneous preparation of nerve-ending particles with physical properties similar to other subcellular organelles. The findings support the idea that acetylcholine and related enzymes are localized within synaptosomes, and that synaptic vesicles are involved in the storage and release of neurotransmitters. The study highlights the importance of proper techniques in isolating synaptic vesicles and the need for careful analysis to avoid contamination. The results provide insights into the structure and function of synaptosomes and their role in neurotransmission.The paper describes the isolation of synaptosomes, which are discrete particles derived from presynaptic nerve endings in brain tissue. These particles retain the structural features of the nerve endings and are separated using differential and density-gradient centrifugation. Synaptosomes contain acetylcholine, choline acetyltransferase, hydroxytryptamine, and noradrenaline, suggesting that these substances are localized within synaptosomes derived from cholinergic and other neurons. Electron microscopy reveals that synaptosomes consist of thin-walled bags containing synaptic vesicles, mitochondria, and cytoplasm. Synaptic vesicles are classified into three types: hollow, dense-cored, and compound. These vesicles are proposed as the binding sites for neurotransmitters within the nerve endings. The study also details the disruption of synaptosomes to isolate synaptic vesicles, mitochondria, and other components. Water suspension was used to release vesicles, and a density-gradient procedure was employed to separate them from membrane fragments and other structures. The results show that acetylcholine is distributed bimodally in the density gradient, with some in synaptic vesicles and some in incompletely disrupted synaptosomes. Lactate dehydrogenase, a soluble cytoplasmic marker, was mainly recovered in the soluble-cytoplasmic fraction, while succinate dehydrogenase, a mitochondrial marker, was mainly recovered in the mitochondrial fraction. Cholinesterase was found in microsomal and large-membrane fractions. The study also compares the results with those of other researchers, noting that some preparations may be heterogeneous and contaminated with membrane fragments. The authors conclude that synaptosomes are a homogeneous preparation of nerve-ending particles with physical properties similar to other subcellular organelles. The findings support the idea that acetylcholine and related enzymes are localized within synaptosomes, and that synaptic vesicles are involved in the storage and release of neurotransmitters. The study highlights the importance of proper techniques in isolating synaptic vesicles and the need for careful analysis to avoid contamination. The results provide insights into the structure and function of synaptosomes and their role in neurotransmission.