Quantitative histochemistry of the vestibular cerebellum of the fish Fundulus heteroclitus flown aboard the biosatellite Cosmos-782.

The fry of Fundulus heteroclitus, hatched from eggs flown for 19.5 d aboard the biosatellite Cosmos-782, showed on Day R+5 a slightly increased activity of creatine kinase at the sites of projection of primary vestibular fibers in the cortex of the vestibular cerebellum. The change was determined by quantitative histochemical analysis. The increase indicates an elevation of the functional activity of the structures of the vestibular cerebellum which developed in zero G and which normally receive primary impulses from gravireceptors.