Sclera in lobe-finned fishes, various reptiles, and birds. The ring has disappeared in many groups, including living amphibians, some reptiles and fish, and all mammals. The eyes of all non-human primates are dark with small, barely visible sclera. The collagen of the sclera is continuous with the cornea. From outer to innermost, the four layers of the sclera are: The sclera is opaque due to the irregularity of the Type I collagen fibers, as opposed to the near-uniform thickness and parallel arrangement of the corneal collagen. Moreover, the cornea bears more mucopolysaccharide (a carbohydrate that has among its repeating units a
Development of the human cerebral cortex Development of the human cerebral cortex Corticogenesis is the process in which the cortex of the brain is created during neurodevelopment. The cortex is the outer layer of the brain and is composed of up to six layers. Neurons formed in the ventricular zone migrate to their final locations in one of the six layers of the cortex The process occurs from embryonic day 10 to 17 in mice and between gestational weeks seven to 18 in humans. The preplate is the first stage in corticogenesis prior to the development of the cortical plate. The preplate is located between the