Effect of spaceflight on rat hepatocytes: a morphometric study.

Hepatic tissue from flight, synchronous, vivarium, and tail-suspended rats was examined by light microscopy and computer-assisted image analysis. Glycogen levels in flight rats were found to be significantly elevated over those in controls. Lipid was also higher but not significantly different. Hepatocytes appeared larger in flight animals because of area attributed to increased glycogen. Sinusoids were less prominent in flight animals than in controls. The total Kupffer cell population appeared to be reduced in flight animals and may represent changes in defensive capacity of the liver. Alterations in the storage of glycogen and number of Kupffer cells suggest an important effect of spaceflight on the function of the liver that may have important implications for long-term spaceflight.