The three-dimensional microanatomy of the liver

Area of Science:

• Hepatology
• Cell Biology
• Microscopy

Background:

• The mammalian liver's three-dimensional (3D) microstructure is crucial for its function.
• Previous studies often relied on two-dimensional (2D) imaging, limiting a comprehensive understanding of the liver's complex architecture.

Purpose of the Study:

• To elucidate the detailed 3D microstructure of the mammalian liver using scanning electron microscopy (SEM).
• To characterize the morphology of hepatocytes, bile canaliculi, sinusoids, and associated cells.
• To investigate potential functional implications of observed microarchitectural features.

Main Methods:

• High-resolution scanning electron microscopy (SEM) was employed to examine the liver's 3D microarchitecture.
• Detailed imaging of liver lobules, acini, hepatocytes, sinusoids, and bile ductules was performed.

Main Results:

• SEM revealed interconnected liver plates, sinusoids, and hepatocytes with distinct surface features (microvilli, smooth areas).
• Bile canaliculi exhibited microvilli, pits, and potential intracellular branches, with close proximity to Disse spaces suggesting diffusion pathways.
• Sinusoidal endothelial cells showed fenestrations, while Kupffer cells displayed macrophage-like characteristics and interacted with endothelial cells.
• The space of Disse was identified as a 3D labyrinth containing collagen fibers, basal lamina, and fat-storing cells.

Conclusions:

• The study provides a detailed 3D ultrastructural map of the mammalian liver, enhancing understanding of cellular interactions and microarchitecture.
• Observed microanatomical features, such as the proximity of bile canaliculi to Disse spaces, suggest specific roles in substance transport and potential pathological mechanisms like bile regurgitation.
• The findings emphasize the importance of SEM in revealing complex microarchitectural details previously unappreciated in 2D studies.