Distribution of spheroidal MVBs and MVBs with tubular protrusions. A. Distribution of MVBs with tubules in dendrites, axons, and nonsynaptic fibers. B Percentage of MVBs with tubules and without tubules (spheroidal) in the six cortical layers. C, D, E. Proportion of MVBs with and without tubules (spheroidal) in dendrites, axons, and nonsynaptic cell processes.