Figure 1.

Cartoon (lower right) summarizing the origins of cortical interneurons and the tangential migratory paths they follow to the developing neocortex (cortical plate and subplate at this stage of development). At first, early born interneurons follow a more ventral route before migrating along the marginal zone overlying the developing cortex. Once the cortical plate has developed, cells in this pathway also migrate along the intermediate zone. Later born neurones follow a more dorsal route and then migrate along the subventricular zone. See insert (top) for layers. On the left, expression patterns of some of the transcription factors that appear to play a role in differentiation and migration are indicated (see color key). The expression of two important extracellular signals, Semaphorin (3A and 3F) and Neuregulin-1 are also indicated. The birth places of somatostatin-containing (SOM), parvalbumin- containing (PV), calretinin- (CR), and calretinin- plus somatostatin-containing (CR + SOM) interneurons are also indicated. Coronal section through the brain of an embryonic mouse (approximately E14). Figure modified from Hernández-Miranda et al. (2010), Heng et al. (2007), Huang (2009b).