The expression of Ultrabithorax (Ubx) during development of the nervous system of Drosophila.

Using a double-staining technique with the neuron-specific monoclonal antibody 22C10 and the anti-Ubx monoclonal antibody FP 3-38 we describe the development of landmark cells in the nervous system of Drosophila. The staining with MAb 22C10 provides an internal system of reference that allows a precise localization of the most prominent Ubx active cells. The expression of Ubx seems to initiate at the segmental border in the hypoderm and the homologous region in the neuromeres. Also, the extent of Ubx expression follows quantitative and qualitative changes during embryonic development.