Cell lineages and oval cell progenitors in rat liver development

Area of Science:

• Developmental Biology
• Hepatology
• Cell Biology

Background:

• The origin of hepatic and bile duct cells during development is not fully understood.
• The potential presence of stem-like cells in the developing liver, similar to those in adult injury models, requires investigation.

Purpose of the Study:

• To determine the association between hepatic primordium formation and liver-specific marker expression in rats.
• To investigate the origin of intra- and extrahepatic bile ducts.
• To identify potential stem-like cells in the developing liver.

Main Methods:

• In situ hybridization to detect alpha-fetoprotein (AFP) mRNA.
• Immunohistochemical methods to detect AFP protein and lineage-specific cytokeratins.
• Histochemical determination of gamma-glutamyl transferase activity and glycogen.

Main Results:

• AFP mRNA is detected in ventral foregut endodermal cells at 10.5 days, with protein appearing one day later, preceding liver morphogenesis.
• Albumin mRNA expression begins just one day after AFP mRNA detection.
• Hepatoblasts show gradual maturation, with AFP- and albumin-expressing cells giving rise to both intra- and extrahepatic bile ducts.
• Developing intrahepatic bile duct precursors share markers with adult liver stem-like cells.

Conclusions:

• AFP expression signifies endodermal cell commitment to the liver lineage.
• Hepatoblasts are the progenitors of both hepatocytes and bile ducts.
• Developing liver contains cells with markers similar to adult liver stem-like cells, suggesting a potential link between developmental processes and regenerative responses.