Fig. 1.

Key features of a prototypical multipolar neuron. A diagram of the synthetic and secretory machinery localization is shown in the upper panel. The Golgi complex is found in the cell body, with smaller outposts in proximal dendrites, especially at large proximal branch points. Ribosomes are highly concentrated in the cell body, with additional clusters in dendrites, especially at branch points. The rough endoplasmic reticulum (RER) is found in the cell body, and the smooth ER reaches into all regions of the cell. Mitochondria are also found in all compartments. In the lower panel, some of the major cytoskeletal components are shown. The axon initial segment (AIS) is an ankyrin–spectrin meshwork under the plasma membrane. Axonal microtubules are uniformly plus-end-out while dendritic ones are typically 50% or more minus-end-out. Dendritic spines rely on actin for their characteristic shape.