|Atlas of Drosophila Development by Volker Hartenstein||Table of Contents|
|Select image to enlarge in new window|
CNS pages 6-7 | 8-9 | 10-11
The precursors of the CNS derive from specialized parts of the ectoderm, the neurogenic regions, which are show here projected on a stage 5 embryo. The ventral neurogenic region gives rise to the neuroblasts of the ventral nerve cord, the part of the CNS belonging to the segmented germ band.
The precursors of the CNS (neuroblasts) derive from specialized parts of the ectoderm, the neurogenic regions, which are shown here projected on a stage 5 embryo (see Campos-Ortega; Goodman and Doe; both this volume). The ventral neurogenic region (VNE) gives rise to the neuroblasts of the ventral nerve cord, the part of the CNS belonging to the segmented germ band (Hartenstein and Campos-Ortega 1984). Separating the ventral neurogenic region from the mesoderm (ms) is the mesectoderm (mec), a single row of cells on either side of the embryo that, among other cell types, gives rise to a number of neuronal precursors. The pro-cephalic neurogenic region (PNE) generates the brain. Adjacent to the procephalic neurogenic region is the anlage of the optic lobe (ol), which develops differently from the rest of the brain (see below). It should be emphasized that the neurogenic regions contain not only neuro-blasts, but also epidermal precursors that give rise to the ventral epidermis and the head epidermis.