[Structural changes in vestibular nuclei of macaca mulatta brain following flight in satellite Bion-11]

The structure of vestibular nuclei cells was studied in the brain of Macaca mulatta on return from the 14-d flight on satellite BION-11 and in 2 days of recovery. The monkey suddenly deceased on day 2 since landing because of aspiration asphyxia on completion of biopsy of muscle and bone tissues. Basic shifts in neural cells of the vestibular nuclei were focal tigrolysis and formation of larger clodlets by remains of tigroid. The most pronounced changes occurred to cells in the medial, upper and descending vestibular nuclei. Deiter's lateral vestibular nucleus was least changed. The conclusion has been made that loss of reactivity by vestibular nuclei in microgravity is linked not only with the effects of exterofactors (otolith and labyrinthine receptors) but also with the structural-functional deficiency of cells of vestibular nuclei.