CHAPTER IV
CONCLUSIONS
A diagrammatic summary of the results of separations
of day 7-8 tectum cells is shown in Fig. 2-12. From the
results presented here it is concluded that A2B5 is an
accurate marker for neurons in long-term monolayer cultures
made from unpurified embryonic chick OT cells. The
immunomagnetic separation procedure used is an extremely
effective technique for the separation of embryonic neural
cell types based on cell surface antibody binding.
Immunomagnetic depletion of A2B5(+) cells, and possibly
neurons, from dissociated embryonic tectum cells resulted
in recruitment of new A2B5(+) cells from cells that
otherwise would not have been recruited.
Recruited cells from day 7 or 8 tissue compensated for
this depletion by presumably developing a purely neuronal
phenotype in vitro. The deleterious effect of polyornithine
>
substrata on recruited cells suggests that the recruited
cells were not initially neuronal and that the acquisition
of the neuronal phenotype was not a single step process.
New DNA synthesis was not required for A2B5 antigen
modulation, nor for neuronal development. It is believed
that it is not possible to purify day 7 or 8 glioblasts
that remain as such unless the A2B5(-) cells that are
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