The cerebral cortex is composed of a large variety of different neuron types. All cortical neurons, except some interneurons, are born in two proliferative zones, the cortical ventricular (VZ) and subventricular (SVZ) zones. The relative contribution of both proliferative zones to the generation of the diversity of the cortical neurons is not well understood. To further dissect the underlying mechanism, molecular markers specific for the SVZ are required. Towards this end we performed a subtraction of cDNA libraries, generated from E15.5 and E18.5 @entity19 cerebral cortex. A novel cDNA, @entity69947 , was cloned which was specifically expressed in the proliferating cells of the SVZ but not the VZ. The VZ is marked by the expression of the @entity5004 gene. Later in development, @entity69947 and @entity5004 were expressed in subsets of cells of upper (II-IV) and deep (V-VI) layers, respectively. In the reeler cortex, where the layers are inverted, @entity69947 and @entity5004 label precursors of the upper and deeper layers, respectively, in their new location. Interestingly, in the @entity7003 /small eye mutant, @entity69947 activity was abolished in the SVZ and in the upper part of the cortical plate while the @entity5004 expression domain remained unchanged. Therefore, using @entity69947 and @entity5004 as cell-type-specific molecular markers for the upper and deep cortical layers we conclude that the @entity7003 mutation affects predominantly the differentiation of the SVZ cells that fail to migrate into the cortical plate. The abnormality of the SVZ coincides with the absence of upper layer cells in the cortex. Taken together our data suggest that while the specification of deep cortical layers occurs in the ventricular zone, the SVZ is important for the proper specification of upper layers.

Cortical upper layer neurons derive from the subventricular zone as indicated by XXXX gene expression.

@entity19 :: ('10090', 'Species') :: ['mouse'] @entity5004 :: ('18423(Tax:10090)', 'Gene') :: ['Otx1'] @entity7003 :: ('18508(Tax:10090)', 'Gene') :: ['Sey', 'Pax6'] @entity69947 :: ('266615(Tax:10090)', 'Gene') :: ['Svet1']
@entity69947 :: (266615(Tax:10090),Gene) :: ['Svet1']
