Quantitative ultrastructural studies of hepatocytes from fed and starved frogs

Stereological analysis of liver tissue excised from mature female Rana pipiens starved for 59 days and from a fed control group was conducted both at the light and electron microscopy levels. Average cellular volume decreased by more than a factor of 4 following prolonged fasting. Nuclear volume was not significantly decreased. Mitochondrial volume per cell showed a slight, though not statistically significant, decrease from 540 μm 3 to 420 μm 3 . Rough endoplasmic reticulum decreased in absolute surface area per cell from 13,600 μm 2 /cell to 3,000 μm 2 /cell after starvation, but its surface density in the cytoplasm remained relatively constant. Lipid decreased from 650 μm 3 per cell to less than 1 μm 3 per cell after fasting. Glycogen decreased from 49% of hepatocyte cytoplasmic volume to less than 15%, a decrease in absolute volume from 4,000–240 μm 3 per cell. Glycogen changed from the α to the β‐configuration during fasting. Condensed cross‐banded fibers or sheets formed within the rough endoplasmic reticulum cisternae of some fasted animals. The significance of these results relative to the energy metabolism of poikilotherms is discussed.