Control of cortical neuron layering: lessons from mouse chimeras

摘要: How is the activation of Reelin signalling within neurons translated into the layering of cortical neurons? To address this question, we made mouse chimeras to test the reciprocal effects of neurons possessing different genotypes but sharing a common cortical environment during development. In chimeras composed of wild‐type and mutant neurons (for either Reelin, Dab1 or p35 genes), a common observation was the formation of a second set of cortical layers on top of an inverted mutant cortex. The secondary cortex was invariably layered in the correct order, and in Dab1 and p35 chimeras, they were principally composed of wild‐type neurons. In contrast to these cellautonomous effects, Reelin chimeras displayed non cell‐autonomous effects. In these chimeras, only a small number of wild‐type neurons were required to be present in order for a secondary cortex to be formed. Interestingly, the principal …