Smooth endoplasmic reticulum and synaptic vesicles in cultured murine neuroblastoma cells

Cultured murine neuroblastoma cells contain an extensive smooth endoplasmic reticulum (SER), also within their numerous processes and their terminals, consisting of a complex network of sacs and tubules. Both the perikaryal and the SER found within the processes and endings resemble one another morphologically. From the SER whether it is within the perikaryon or within the terminals of the neural processes, round coated vesicles with clear centers appear to form. These clusters of vesicles are 40...60nm in diameter and indistinguishable from the synaptic vesicles of normal neurons. In addition a few vesicles with clear centers with a diameter of 20...40 nm and length of 80...200 nm are encountered and appear to originate from the SER. The dense-cored vesicles do not seem to develop from the SER. There is no detectable association of the vesicles with any other cell organelle.