Choroid Choroid The choroid, also known as the choroidea or choroid coat, is the vascular layer of the eye, containing connective tissues, and lying between the retina and the sclera. The human choroid is thickest at the far extreme rear of the eye (at 0.2 mm), while in the outlying areas it narrows to 0.1 mm. The choroid provides oxygen and nourishment to the outer layers of the retina. Along with the ciliary body and iris, the choroid forms the uveal tract. The structure of the choroid is generally divided into four layers (classified in order of furthest away from the
Development of the human cerebral cortex in this area is where neurons, that are created in the ventricular zone, migrate through in order to reach the cortical plate. This zone is only present during corticogenesis and eventually transforms into adult white matter. The ventricular and subventricular zones exist below the intermediate zone and communicate to other zones through cell signalling, also creating neurons destined to migrate to other areas in the cortex. The marginal zone, along with the cortical zone, make up the 6 layers that form the cortex. This zone is the predecessor for layer 1 of the cortex. Astrocytes form an outer limiting membrane