Contribution of transit amplifying type-II neuroblast lineages to central complex primordium formation and optic lobe glial cells in drosophila melanogaster

In this thesis, early born neurons of transit amplifying type-II neuroblast lineages were analyzed in the central brain of Drosophila melanogaster. A subset of these early-born neurons play an important role in building an adult specific neuropil structure called the central complex which is involved in locomotion and visual memory. We studied the formation of this central complex primordium by early born type-II neuroblast derived neurons and followed its development through larval live into the adult. Further single cell reconstructions undertaken in a serial section electron microscope stack of the early first larval instar brain revealed the embryonic formation of the central complex primordium by type-II neuroblast lineage derived neurons. The specific topological organization of the central complex primordium is already present at early first larval instar. Morphological analysis showed, that at this stage the primordium is made by undifferentiated cells which are devoid of synapses. The characterization of the embryonic born neurons of one specific type-II neuroblast lineage revealed other types of undifferentiated neurons as well as a high diversity of differentiated larval functional neurons.
In summary, type-II neuroblast lineages were shown to produce a high diversity of neurons during embryonic development of Drosophila melanogaster. A subset of these neurons gives rise to a neuropil primordium which will develop into the central complex during metamorphosis.