The liver of Testudo graeca (Chelonia). A comparative study of hibernating and non-hibernating animals

Abstract

In the present work, a comparative study of the liver of hibernating and non-hibernating specimens of Testudo graeca (Chelonia) has been carried out by light and electron microscopy. During hibernation, the morphological changes which take place do not affect the general architecture of the liver, but are mainly concerned with the number and distribution of the cytoplasmic organelles and reserve materials in the hepatocytes. In non-hibernating animals, the cytoplasm of the hepatocytes has a large number of organelles indicating a high cell activity, as well as numerous lipid droplets and glycogen. In hibernating animals, the size of the hepatocytes is reduced and the cytoplasm is vacuolated. There is also an increase in lysosomal activity due to the increase in the number of secondary lysosomes in the cytoplasm. Sacs full of degenerating hepatocytes can be observed among the hepatic cells. Glycogen and lipid droplets are not present in the hibernating animals. The present study demonstrates that, during hibernation, the hepatocytes likely undergo ultrastructural changes related to the synthesis, storage and release of reserve material.