title: Phylogenetic and ecological features of the structural organization of the forebrain cortical plate in Chelonia: 1. Neuronal composition and dendrite spines of the cortical zones in land and aquatic Chelonia.
abstract: A comparative study was made of cytoarchitectonics, neuronal composition and ultrastructural organization of the three basic cortical zones (hippocampal, dorsal and pyriform) of the forebrain of four members of Chelonia (two aquatic and two land species). The features under study fall into three major groups as follows: (1) common to all the Chelonia under investigation and possibly of the entire order; (2) ecologically specific, i.e. common to animals with similar ecology and different in animals with different ecology; (3) species-specific, i.e. differing in individual species. The common structural features of the forebrain cortical plate in Chelonia underlie the morphological substrate responsible for specific functions in different cortical zones. It is precisely with respect to the common features that the dorsomedial dorsal cortex exhibits a more complex neuronal and synaptic organization as compared with other cortical zones. This part of Chelonia cortex is assumed to be homologous to mammalian neocortex. The more plastic ecologically specific and species specific features appear to provide adaptive specializations within a particular level of the nervous system organization.
mesh_terms: D000818:Animals; D002540:Cerebral Cortex / Q000033:anatomy & histology*; D003712:Dendrites / Q000648:ultrastructure*; D004292:Dominance, Cerebral / Q000502:physiology; D004463:Ecology; D006624:Hippocampus / Q000033:anatomy & histology; D008032:Limbic System / Q000033:anatomy & histology; D008854:Microscopy, Electron; D009474:Neurons / Q000648:ultrastructure; D010802:Phylogeny; D013045:Species Specificity; D014426:Turtles / Q000033:anatomy & histology*