[Mitotic activity and the nuclear volume of the epithelial cells of the rat cornea after a space flight on biosatellites].

On total preparations of the cornea of rats flown on Cosmos-936 and Cosmos-1129 the following parameters of the epithelial mitosis were studied: mitotic index, ratio of mitotic phases, number of abnormalities of cell division, and number of chromosome aberrations in anaphases. These parameters were considered to be indicators of physiological regeneration. The nuclear volume of cells of two inner epithelial layers was measured, using a modified karyometric technique that yielded representative data. The lack of significant changes in the above mitotic parameters can be attributed either to the absence of a strong stress-reaction of rats postflight or to the discrepancy between the time of animal sacrifice and the time of the maximum post-stressor inhibition of mitotic activity. This study revealed some data suggesting that in weightlessness the rate of cell division remained unaltered. The mean nuclear volumes of corneal epithelial cells changed significantly (P less than 0.01) at late examination stages (days 6 and 29). This may be associated with rearrangements in the regulatory systems of the animal body postflight. It cannot be ruled out that an increased cell activity measured with respect to the nuclear size correlates with the intraocular pressure.