FIGURE 3 | The spinal cord is patterned along its dorsoventral axis.

A schematic illustration of the roof plate, which expresses bone morphogenetic proteins (BMPs) as well as other transforming growth factor- (TGF) family members, and the floor plate, which expresses sonic hedgehog (SHH). The neural progenitor cells are first divided into broad dorsoventral domains by the differential expression of Pax homeobox genes (left side). BMPs activate the dorsal Pax genes and set the expression domain boundary of Pax6 by repressing it in the dorsal spinal cord. The spinal cord is further subdivided by the expression of basic helix–loop–helix (bHLH) family and homeodomain transcription factors (right side). This process is also tightly regulated by BMP signalling. High levels of BMP signalling set up the most dorsally located Math1 domain and lower levels of signalling define the less dorsal cell populations, which express neurogenin 1 and 2 (NGN1/2) and the transcription factor Mash, repectively. The regionalization of the precursor cells leads to formation of distinct dorsal and ventral neuronal cell types, namely the dorsal interneurons (dI1–6), the ventral interneurons (V0–3) and the motor neurons (MN).

Download file

If the slide opens in your browser, select "File > Save As" to save it.