ABSTRACT
We 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 o f white matter and decreased volume o f the retina, olfactory placodes and VIII cranial nerve ganglion size. Asymmetrical development of cerebral structures o iX . laevis was, however, unaffected by spaceflight. Embryonic rats exposed to microgravity from days 9-20 o f 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.
