Electron Microscopic Observation of Cholinesterase Activity in the Developing Neuromuscular Junction of Urodele, Hynobius nigrescens(Developmental Biology)

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Cholinesterase (ChE) activity in the neuromuscular junction (n-m-j) of the developing urodele was electron microscopically studied. Early sign of myogenesis was first observed in stage 43 in which mesenchymal cells were differentiated to have myofilaments without z-band material. These early myoblasts showed the reaction products of ChE activity in smooth endoplasmic reticulum (s-ER) and vacuoles. Nerve fibers were not in close contact with these myoblasts. At the same time, nerve-muscle contacts at varied developmental levels were encountered. Mere apposition of both plasma membranes in about 100 nm intercellular space characterized the most primitive form. On the surface of myoblasts surrounding such contacts, extracellular end products in the flocculent coat were present. These myoblasts had myofilaments with z-band material. In the axoplasm facing a myoblast there was an aggregation of uniform small vesicles of the size of synaptic vesicles. Deposition of end products was seldom observed in nerve fibers. More differentiated nerve-muscle contacts which showed increased density in sarcolemma and formation of single basal lamina accompanied by ChE activity were also seen in stage 43. Thus, it should be mentioned that the extracellular ChE activity in the early nerve-muscle contacts became detectable prior to the maturation of n-m-j.
社団法人日本動物学会の論文
1985-06-15