Human brain 13th gestational week

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By the end of 11th pcw (13 gw) cerebral hemispheres (hemispherium cerebri) enlarge threefold from the beginning of the 10th gw. Hemisphere length measures up to 30 mm. Mesencephalon is covered by the hemispheres, which close to anterior rim of cerebellum, from the lateral view. The trough of the ventrolateral hemispheric wall increases forming primary area of the insula, which resulted in temporal lobe segregation.

At this stage cortical plate initial consolidation is finishing. Hemispheric walls possess the following structures: ventricular zone adjacent the lateral ventricle cavity, then subventricular and intermediate zones follow, adjoining cortical plate. The marginal zone borders externally with pia mater. Also at this stage, the ventrolateral part of the cortical plate becomes sparse, due start of the formation of the subplate.