The term homotypic cortex refers to those areas of the neocortex that retain into adulthood the homogeneous six- layered internal structure of neocortex in the third trimester of gestation. It is contrasted to heterotypic cortex, which is neocortex that does not retain the fetal six-layered pattern. By far the majority of neocortical areas remain homotypic ( Brodmann-1909 ).