Morphology and growth of embryonic, XXXX dorsal root ganglion explants in long-term culture: expression of cell type-specific markers during early differentiation.

@entity1 @entity2901 @entity5399 @entity2281
Embryonic, @entity1 spinal ganglion explants were plated at 5-12 weeks postconceptional age and cultured for 5-50 days on a semisynthetic substrate in a serum-containing culture medium without addition of antibiotics or preconditioned medium. The growth pattern in vitro was found to be age dependent. Five- to 6-week ganglia showed a characteristic semicircular growth pattern with bidirectional extension of neurites on top of a monolayer of supportive cells. Explanted 9- to 10-week ganglia showed an extensive, multidirectional neurite outgrowth with less pronounced proliferation of nonneuronal cells. Neurite extension, @entity2901 , cell migration and morphology were studied immunohistochemically with antibodies to neurofilament (NF), @entity2281 , and the @entity5399 glycoprotein. Both NF and @entity2281 were expressed at 5 weeks gestational age in ganglionic neurons and in proliferating Schwann cells in contact with axonal processes, respectively. NF was homogeneously distributed in both cell somata and neurites, whereas @entity2281 immunoreactivity showed an intense nuclear and a weaker cytoplasmic distribution in spindle-shaped, bipolar Schwann cells. This staining pattern was conserved during differentiation in long-term culture. @entity5399 was expressed on ganglionic neurites forming fascicles by the third week in culture. However, @entity5399 was never expressed until the total age of 10 weeks. In addition, @entity5399 was found on fibroblasts from the first week in culture. The distribution of @entity5399 on the cytoplasmic membrane was similar in both cell types, showing a coarsely granulated membrane staining. The temporal as well as the spatial expression of differentiation antigens in tissue sections of early embryonic spinal cord and spinal ganglia were very similar to what was observed in vitro.
