RESUMEN
Rat adrenals were studied using histological and histochemical methods during prolonged intoxication with pesticide magnesium chlorate which was administered in a dose equal to 1/100 of LD50 (41 mg/kg of body weight). Animals that received distilled water and were kept in similar conditions were used as control. It was demonstrated that intoxication of rats for 3-7 days results in increased secretory activity of all the zones of adrenal cortex. Later (after 14-90 days) the zonal response to pesticide administration was variable. Magnesium chlorate treatment results in the disturbances of hormonal synthesis in adrenocorticocytes. Compensatory-adaptive capacities of zona fasciculata were found to be greater than those in zona glomerulosa and zona reticularis.