Phenotypic plasticity of 'mature' human fœtal mesencephalic dopaminergic neurons and glial cells

Human mesencephalic neurons from the second trimester have been cultured and characterised. Fresh, non-cultured cells were rounded and without processes post-dispersion but in culture differentiated with neurite outgrowth when treated with 2 mMdibutyryl cyclic AMP in the absence of serum. This morphological differentiation could be reversed by the addition of the serine protease, prothrombin. Immunocytochemical staining for dopamine, tyrosine hydroxylase, neuron-specific enolase and glial fibrillary acid protein, demonstrated that dopaminergic, non-dopaminergic and glial elements responded similarly. The conditioned medium contained quantifiable levels of catecholamines as measured by HPLC. These findings are relevant to both developmental neurobiology and clinical neural transplantation, evidencing the considerable plasticity and functional integrity of mesencephalic cells in the second trimester as well as the influence of environmental factors.