Glial interactions with neurons during Drosophila embryogenesis.

A monoclonal antibody (Mab5B12) demonstrating specificity for glial cells within the central and peripheral nervous systems of Drosophila has been used in combination with neural-specific antibodies to study the early organization of the Drosophila embryo. The embryonic central nervous system of Drosophila contains cells within the ventral midline that are recognized by monoclonal antibody 5B12. These cells are not recognized by either a polyclonal antiserum to horse radish peroxidase, which recognizes several antigens on the surface of Drosophila neurons, or Mab22C10, which recognizes an antigen specific to the peripheral nervous system. Mab5B12-positive cells lie dorsal both to the developing anterior and posterior commissures in each thoracic and abdominal segment and to the supraoesophageal commissure. They ensheath these commissures in later stage embryos. Other Mab5B12-positive cells lie dorsolateral to the CNS and send processes laterally to the lateral sensilla during axonogenesis in the PNS. These cells surround the axons of the intersegmental and segmental nerves. Other cells that line the advancing ectoderm during dorsal closure and surround the anal pads also express the Mab5B12 antigen. Neuronal cell cultures derived from Drosophila gastrulae contain cells expressing the Mab5B12 antigen. These cells can be found separate or in close association with neuronal clusters and their axons.