Development of vertebrate brain asymmetry under normal and space flight conditions

W c investigated the effects of spaceflight on the development of right-left brain asymmetry in larvae of amphibians (Xenopus Laevis) and in pups and embryos of mammals (Rattus norvegicus). Here we report that larvae of X laevis showed no changes in the volume of grey matter post exposure to microgravity, but did show increased volume of white matter and decreased volume of the retina, olfactory placodes and VIII cranial nerve ganglion size. Asymmetrical development of cerebral structures of X laevis was, however, unaffected by spaceflight. Embryonic rats exposed to microgravity from days 9-20 of development had widespread neurodegeneration and, additionally, formed grey matter cavities. From a symmetry perspective, histological and morphometrical analysis found that space flight conditions reversed the typical left -> right-sided enlargement of the nuclei habenulae and nuclei colliculi, and produced abnormalties in neural migration.