A Stereological Study on Size and Number of Mitochondria in Zona Fasciculata of Rat Adrenal Cortex after Whole-body X-irradiation

Summary

The weight of the zona fasciculata in rat adrenal cortex increased to about 50 per cent over the control during the period of 72 hours after whole-body x-irradiation of 1000 R. The mitochondria of the parenchymal cells in the zona fasciculata were reconstructed three-dimensionally by Bach's theory on sphere-size distribution, using electron micrographs recorded at random during the post-irradiation period. The average volume of mitochondria was significantly larger than the control at 24 and 48 hours, but smaller at 72 hours after 1000 R. The total number of these mitochondria in an individual rat decreased to 60 per cent of the control at 24 hours and then increased to about twice the control at 72 hours. The size-distribution histograms showed that small mitochondria with radii shorter than 0·3 μ are practically absent in the control and in the groups at 24 and 48 hours, but present in the rats at 72 hours.