Analysis of gene expression patterns in the developing chick liver

Abstract

The chick embryo has been used widely for studying liver development. However, in the past 30 years, the usage has decreased markedly due to lack of appropriate marker genes for differentiation in the developing chick liver. To use the chick embryo for analyzing the molecular mechanism of liver development, we surveyed marker genes in the developing chick liver by examining the expression pattern of genes that are well-characterized in the developing mammalian liver. By whole-mount in situ hybridization, Fibrinogen-gamma (FIB) expression was first detected at stage 12, specifically in the anterior intestinal portal, and its liver-specific expression persisted in the later stages. Albumin (ALB) expression was first detected at stage 30, when the liver starts maturing. Cytokeratin 19 (CK19) was first detected at stage 37 in the ductal plate of the liver, and its expression continued in the intrahepatic bile ducts derived from the ductal plate. Hex, a transcription factor, is an additional marker of bile duct differentiation. Hence, FIB, ALB, and CK19 expression can be used to trace hepatic induction, maturation, and bile duct differentiation, respectively.