The Normal Hepatocyte
A healthy liver cell stores almost no visible fat.
- ~240 B: Hepatocytes per liver (the main liver cell type)
- <5%: Normal lipid content (of cell volume)
- ~1.5 kg: Liver mass (largest internal organ)
- High: Regeneration capacity (can regrow from partial loss)
A metabolic powerhouse
Hepatocytes process nutrients, toxins, and bile continuously.
Fat handling in balance
Fatty acid uptake and export normally stay balanced.
Why this cell matters
This single cell view anchors every later disease stage.
Lipid Droplets Begin to Accumulate
Excess energy intake pushes fat storage past a healthy limit.
- ~32%: Global MASLD prevalence (of adults worldwide)
- >5%: Steatosis threshold (hepatocyte fat by weight)
- High: Reversibility (with weight and diet change)
- Silent: Symptom burden (usually asymptomatic stage)
Droplets fill the cytoplasm
Triglycerides pack into growing round lipid droplets.
Driven by metabolic risk
Obesity, insulin resistance, and diet raise fat delivery.
Still a reversible stage
Simple steatosis alone rarely damages the cell yet.
Ballooning Degeneration and Inflammation
Overloaded hepatocytes swell, and immune cells rush in.
- ~5%: MASH prevalence (of adults worldwide)
- CK-18: Ballooning marker (cytoskeletal collapse signal)
- Kupffer: Key inflammatory cells (liver-resident macrophages)
- Elevated: Oxidative stress (lipotoxic cell injury)
The cell balloons
Cytoskeleton collapse makes the membrane swell and distort.
Immune cells infiltrate
Macrophages and lymphocytes cluster around injured hepatocytes.
A tipping point
MASH marks the shift from fat storage to injury.
Why it matters clinically
Only inflamed, ballooning livers tend to progress further.
Collagen Deposition Around the Cell
Repeated injury triggers scar-forming collagen around hepatocytes.
- F0–F4: Fibrosis staging (METAVIR scoring system)
- HSC: Key producer cell (activated hepatic stellate cells)
- Type I: Main collagen type (dominant scar protein)
- Duration: Progression driver (years of ongoing injury)
Stellate cells activate
Chronic injury turns quiet stellate cells into scar producers.
Fibers wrap the cell
Collagen strands encircle the hepatocyte in thin bands.
Time is the multiplier
Longer disease duration deposits denser collagen networks.
Dense Fibrotic Bands Replace Architecture
Scar tissue overwhelms the cell, replacing normal structure.
- F4: Fibrosis stage (cirrhosis, bridging scar bands)
- >1M/yr: Global cirrhosis deaths (end-stage liver disease)
- Low: Reversibility (architecture is largely fixed)
- HCC: Downstream risk (elevated liver cancer risk)
The cell is engulfed
Dense collagen bands surround and compress the hepatocyte.
Function is lost
Scar tissue replaces working liver architecture permanently.
The end stage
Cirrhosis is the final common pathway of chronic injury.