Sclera pass. The thickness of the sclera varies from 1mm at the posterior pole to 0.3 mm just behind the rectus muscle insertions. The sclera's blood vessels are mainly on the surface. Along with the vessels of the conjunctiva (which is a thin layer covering the sclera), those in the episclera render the inflamed eye bright red. In many vertebrates, the sclera is reinforced with plates of cartilage or bone, together forming a circular structure called the sclerotic ring. In primitive fish, this ring consists of four plates, but the number is lower in many living ray-finned fishes, and much higher
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