Ultrastructural study of the pit cell in a freshwater teleost liver

This report includes the first ultrastructural description of pit cells in a teleost liver. These cells are found in the vicinity of biliary ductules, between hepatocytes, beneath the endothelial lining of blood vessels, in the hepatic capsule, and in the lumen of sinusoids. Although their characteristic granules are concentrated in certain preferential regions of the cell they are not entirely polarized to one side of the nucleus. The function of pit cells is unknown but their morphological characteristics suggest an endocrine function.