The tripartite structure of the undercoat in initial segments of Purkinje cell axons
The undercoat of the initial axonal segment can be resolved into a three-layered structure. Directly beneath the axolemma lies the layer of granules. Each granule is 75 Å in diameter. The granules are arranged in rows that are separated from one another by clear spaces of 75 Å in the long axis of the axon and by about 95 Å in the transverse plane. Deep to this is a dense lamina about 75 Å thick. The third component may be a ridge made up of a web of 50 Å filaments forming a continuous spiral winding beneath the dense lamina.
Key wordsPlasmalemma Cerebellar Cortex Microtubules Synapses Myelin Sheath
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