Figure 10.

Our current model of adult neurogenesis in the crayfish P. clarkii, beginning with hematopoietic tissue, the release of hematopoietic stem cells, their attraction to the niche and transformation into niche cells. These aspects of our model are hypothetical. The niche cells (1^st generation neuronal precursors), which label for glutamine synthetase, divide symmetrically to produce daughters that migrate along processes of the niche cells towards cell cluster 9 or 10. These 2^nd generation neuronal precursors divide at least once more in the proliferation zones in the cell clusters, before differentiating into neurons. These aspects of the model are supported by several types of data, reviewed in this paper.