Interspecies Avian Brain Chimeras Reveal That Large Brain Size Differences Are Influenced by Cell–Interdependent Processes

摘要: Like humans, birds that exhibit vocal learning have relatively delayed telencephalon maturation, resulting in a disproportionately smaller brain prenatally but enlarged adulthood relative to non-learning birds. To determine if this size difference results from evolutionary changes cell-autonomous or cell-interdependent developmental processes, we transplanted telencephala zebra finch donors (a vocal-learning species) into Japanese quail hosts during the early neural tube stage (day 2 of incubation), and harvested chimeras at later embryonic stages (between 9–12 days incubation). The donor host tissues fused well with each other, known major fiber pathways connecting parts brain. However, overall sizes chimeric were larger than non-transplanted same stages, even though proportional telencephalic subregions tracts similar normal finches. There no significant midbrains, they innervated by physically brain, including retinae eyes. Chimeric had decreased cell density nucleus differences between species maintained as These suggest development is partially cell-interdependent, mechanisms controlling different regions may be functionally independent.