Distribution of the cholinergic-specific antigen Chol-1 in mouse spinal cord neurons developing in culture.

The distribution of the cholinergic-specific ganglioside antigen Chol-1 has been studied by indirect fluorescence immunohistochemistry in mouse spinal cord neurons developing in vitro. Chol-1 is first detected after 9 days of culture where it can be seen in the cell bodies of neurons and in the proximal part of their processes. In cultures of the same age, staining with antisynaptophysin antibody revealed that synapse formation has already taken place and the level of choline acetyltransferase activity was found to have reached a plateau. After 12 days in culture Chol-1 can still be seen in the cytoplasm of certain neurons; however, the anti-Chol-1 staining is now more intense in the region of nerve terminals. Anti-neurofilament staining of cultures at this stage reveals that the neurons are highly differentiated and possess an extensive network of processes. These results show that Chol-1 is expressed late in the development of cholinergic neurons after they have formed synapses; it then appears to be transported to the nerve terminal where it accumulates.