[Effect of stressors on the mitotic regime and certain cell cycle events in the corneal epithelium of adrenalectomized rats].

It was established previously that depression of the mitotic activity in the rat cornea induced by pyrogenal administration and exposure to cooling was not attended by changes in the level of labeled nuclei (LLN) and pathological mitoses (PM). This paper shows that adrenalectomized rats developed an increase in PM from 3.9--4.6% (control animals) to 13..9--16.8% (animals exposed to cooling or given pyrogenal). This increase was associated with the reduced LLM and label intensity. Cytophotometric analysis of the DNA content in the nuclei revealed an increase in the number of tetraploid nuclei from 3.2% (in the cornea of intact rats) to 10.9% in rats with adrenals, 6 hours after pyrogenal administration. This phenomenon was accounted for by prolongation of G2M phase. The action of the stressor on adrenalectomized animals produced no changes in tetraploid nuclei. The evidence obtained indicates that the stressor-induced increase in the level of PM in the cornea of rats with reduced adaptability is not a single event in the cell cycle.