A Phase Contrast Microscopy Study of X-Ray-Induced Pyknosis in the Living Cell

Abstract

Summary

The effect of X radiation with 25,000 r can be kept latent in Melanoplus differentialis embryos for 6 months by maintaining them at submetabolic temperatures. In the resting grasshopper nucleus chromatin, in Belar's saline solution, is visible with the aid of phase contrast microscopy. When the eggs are irradiated and placed immediately at 0°C and kept at this temperature for 6 months no immediate morphological or physiological changes are observed upon returning them to 25°C. However, pyknosis occurs by 8 days at 25 °C depending on the irradiation and on the metabolic activity of the cell. Pyknosis in the living cell as observed by phase contrast microscopy resembles fixed material morphologically. Physiologically there is a difference in the physical state of the nuclei when observed in the living condition. Most nuclei show a drop in viscosity at the time of pyknosis as judged by the increase in Brownian movement. Vital staining with Janus green indicates that the mitochondria usually clump as a separate body whereas, the chromatin material becomes pyknotic containing lipoid impregnated bodies.