Cholangiovenous reflux pathways as defined by corrosion casting and scanning electron microscopy

Area of Science:

• Hepatobiliary system research
• Microcirculation and fluid dynamics
• Gastroenterology and internal medicine

Background:

• Understanding the pathways for bile to blood reflux is crucial for managing infections and toxin spread.
• Previous studies have not precisely defined the size and location of cholangiovenous reflux pathways.

Purpose of the Study:

• To investigate the site and size of pathways enabling bacterial reflux from the rat biliary tree to the bloodstream.
• To determine the pressure-volume relationship during retrograde filling of the rat biliary tree.

Main Methods:

• Corrosion casting and scanning electron microscopy (SEM) of rat biliary trees.
• Retrograde injection of resin with varying particle sizes (150 A, 1.7 µm, 10 µm) into the biliary tree.
• SEM examination of intact livers with casted biliary trees without corrosion.

Main Results:

• Cholangiovenous reflux initiates from bile ductules into the spaces of Mall and Disse, then into hepatic sinusoids, occurring at pressures between 20-50 cm water.
• Sinusoid filling progresses with increased volume, and collecting veins are filled above 160 microliters.
• Reflux of particles up to 1.7 µm was observed, but 10 µm particles did not reflux, indicating pathway size limitations.

Conclusions:

• Cholangiovenous reflux occurs directly from bile ductules through the spaces of Mall and Disse into hepatic sinusoids.
• The identified reflux pathways range from 1.7 to 10 µm in diameter.
• These pathways represent the path of least resistance and may be significant for bacterial and toxin reflux into the bloodstream.