Central Nervous System

4535 Words Jun 24th, 2012 19 Pages
Generation of pattern and diversity in Central Nervous System

Central nervous system (CNS) is composed of brain and the spinal cord. Neurons constitute a major part of the developing CNS. An axon is an extension of a neuron. The brain grows as a swelling at the front (rostal) end of the neural tube and later leads to become a spinal cord (1,2). Development of the CNS involves many complex mechanisms beginning at the onset of transformation of a single layer of ectodermal cells, the neuroectoderm until the end of the differentiation process resulting into highly complex structure involving variety of neural cell types (1,2). A large number of cell types need to be arranged spatially and temporally to form a complex structure during an
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A distinct subset of cells (roof-plate) can be identified on the dorsal midline along the entire anterior- posterior axis of the CNS. Roof-plate acts as an organizing center that control mechanisms of dorsal CNS development. With the closure of dorsal end (caudal) of neural tube, arise the interneuron progenitors with non-overlapping expression of Basic helix-loop-helix (bHLH) Transcription factors (TFs) including Math1, Ngn1/2 and Mash1 in the ventricular region of the developing dorsal spinal cord. (6)

Mediators of roof-plate patterning activity in a developing spinal cord include secretory factors of BMP and Wnt signaling cascades. (6,7) It has been documented that there is a mutual antagonistic effect between Wnt and BMP signaling pathways in regulation of differentiation and proliferation of neuroepithelial cells in the dorsal spinal cord. (8). Several other signaling pathways like the retinoic acid signaling and homeodomain TF- Lbx1expression in a group of interneurons is found to be crucial for dorsal spinal cord development. However, there are evidences that had shown roof plate dependent patterning in the rostral (anterior) CNS. It is also hypothesized to influence the development of dorsal hindbrain and forebrain. (6)

The vertebrate CNS is a very

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