117
present in purified cultures. Galactocerebroside(+)
oligodendrocytes were present in dissociated cells from
this age, were all A2B5(-), and apparently continued to
grow in culture. Only a small percentage of cells, all
A2B5(-), incorporated 3H-thymidine during the first 24
hours in culture of either unpurified or purified cells.
Continuous labelling of monolayer cultures resulted in
labelling of the majority of A2B5(-) flat cells, and of no
A2B5(+) neurons, no A2B5(+) nonneuronal cells, and no
oligodenrrocytes. Thus, new DNA synthesis was not required
for the recruitment of A2B5(+) cells or presumably their
differentiation in culture.
It is concluded that the phenotypic instability of
the recruited cells from day 12-13 tissue reflected an
unsuccessful attempt at developing a neuronal phenotype in
vitro. This most likely was due to a restricted
developmental potential of the reactive cells.