Ultrastructural characterization of the death process of hepatocytes in neonatal mouse liver

Introduction Hematopoiesis in mouse fetal liver starts at 10 days of gestation and begins to decline after 15 days of gestation [1]. During postnatal hematopoietic involution, hepatocyte volume rapidly increases, and four types of specialized junctions; i.e., adherens junctions, desmosomes, tight junctions and gap junctions, appear to be fully developed in liver cells [2]. Neonatal livers examined by the TUNEL method contain numerous positive cells. Fetal liver contains cells undergoing apoptosis [3], and the majority of dying cells are hematopoietic cells. However, in addition, a few TUNEL-positive hepatocytes are observed in neonatal livers. The aim of this ultrastructural study was to clarify the hepatocyte death processes in mouse neonates.