Parenchymal cells proliferate and differentiate in an organotypic slice culture of the neonatal liver

We applied organotypic slice culture of neonatal mouse liver tissues to mai ntain the parenchymal cells in ontogenesis and to investigate their prolife ration and differentiation. Cultured tissue spread gradually over 3 weeks. Small basophilic cells formed several layers in the center of the cultured tissues, and a monolayer of polygonal cells was seen at the periphery. Albu min- and alpha-fetoprotein-immunoreactions were seen in polygonal cells, as were proliferating cell nuclear antigen-immunoreactions. Connexin 32- and 26-immunoreactions were observed in small plaques on the membrane of the po lygonal cells, and electron microscopy showed gap junctional complexes. Ult rastructurally, polygonal cells had a round nucleus and abundant cytoplasmi c organelles, and bile canaliculi were seen on the cytoplasmic membrane. Cy tokeratin 19-immunoreactions were scattered in clusters. There were ultrast ructurally bile-duct-like structures with microvilli on the inner surface o f the cavity and tight junctions between their constitutent cells. Quantita tive analysis of albumin-, alpha-fetoprotein- and cytokeratin 19- or prolif erating cell nuclear antigen-immunoreactivity in parenchymal cells showed c hanges of their phenotypes or maintenance of their proliferation in tissue culture. Our slice-culture system enabled us to maintain and to develop par enchymal cells in the Liver tissue for at least 3 weeks. The findings sugge st that organotypic slice culture applied to liver tissues in ontogenesis m ay be a useful tool not only to maintain parenchymal cells but also to inve stigate their proliferation and differentiation.