Influence of tongue myoblasts on rat dissociated hypoglossal motoneurons in culture.

Hypoglossal motoneurons of 1-2 day-old newborn rats were retrogradely labelled following an injection of fluorescent latex microspheres and carbocyanines. Motoneurons were identified among the cell population of the hypoglossal nuclei during the dissociation and culture procedures. DiI labelled motoneurons could be maintained in culture on poly-L-lysine coating and Dulbecco Minimum Essential Medium with Ham F12 complement, supplemented with additives and 3% fetal calf serum. Neuronal survival as well as extension of neurites, identified by their content in DiI or by the presence of choline acetyltransferase immunoreactivity, was increased in the presence of myoblastic satellite cells originating from tongue muscular explants. Co-cultures of dissociated hypoglossal cells with tongue myoblasts revealed the presence, after 10-15 days in culture, of structures morphologically similar to neuromuscular junctions. Such re-innervated muscular fibres exhibited muscular contractions which were blocked by curare and augmented by glutamate applications, demonstrating the functionality of the observed re-innervations.