The CNS midline cells are required for the identity determination and formation of Drosophila CNS

The Drosophila embryonic central nervous system (CNS) develops from sets of neuroblasts which segregate from the ventral neuro-ectoderm during early embryogenesis. It is not well established how each individual neuroblast in the ventral neuroectoderm acquires its characteristic identity along the dorsal-ventral axis. The role of the CNS midline cells in the fate determination of Drosophila ventral neuroectoderm was investigated using several molecular markers for the identified ventral neuroblasts, neurons, and axon pathways. This study showed that the CNS midline cells are required for the expression of neuroblast-specific marker genes from S1 to S5 stages of neurogenesis, indicating that the CNS midline cells are essential for neuroblast identity determination. The CNS midline cells are also required for the proper formation of neurons and axon pathways. This study indicates that the CNS midline cells play important roles in the fate determination of neighboring ventral neuroblasts along the dorsal-ventral axis of the ventral neuroectoderm.