(a).

Zebrafish liver		Zebrafish pancreas		Zebrafish gut
Size	12 dpf: volume = 5 061 840 µm3. Transverse diameter = 349 µm. Anterior-posterior diameter = 520 µm Adult: volume = 0.535 mm3. Transverse diameter = 2.08 mm. Anterior-posterior diameter = 1.64 mm. (In males, ∼2.10% of total body weight. In females, ∼4.51% of total body weight)	Size	12 dpf: Volume = 1 738 670 µm3. Transverse diameter = 290 µm. Anterior-posterior diameter = 500 µm Adult: volume = 0.3 mm3. Transverse diameter = 1.9 mm. Anterior-posterior diameter = 2.5 mm	Size	Long tube of about 400 µm. The interior is also folded and lined with a layer of simple columnar epithelium
Location	Posterior to inner ears and pharyngeal pad, anterior to intestinal bulb	Location	Between the intestine and the swim bladder. The head starts right posterior to the liver	Location	From esophagus to anus
Shape	3 lobes, boomerang shape. The left lobe, the largest, crosses the midline, under the swim bladder and the right lobe extends ventrally towards the head of the pancreas	Organisation	The pancreas is very diffused and acinar cells are scattered	Oesophagus	Located under the trachea. Short and muscular
Organisation of hepatocytes	Tubular	Endocrine tissue	One principal islet (or Brockman body) in the head (50 μm diameter). 2-3 secondary islets surround the principal islet	Composition	Mostly goblet cells and a few enterocytes
Composition	Hepatocytes, endothelial cells, bile duct epithelial cells. Kupffer cells seem to be absent	Beta cells	Insulin granules (160 nm)	Role	First place of enzymatic digestion
Hepatocytes	65% of total liver volume	Alpha cells	Glucagon granules (182 nm)	Intestinal bulb	Dilated, up to 80 µm in diameter
Size	Polygonal, 14–17 µm in size. Hepatocytes form plates, lined with sinusoids and biliary ducts	Other-cells	Delta-cells produce somatostatin	Composition	Enterocytes with very long microvilli at the beginning (up to 7.5 µm long and 115 nm in diameter) and then shortened to 2-3 µm long
Organelles	Nucleus, rER, mitochondria, Golgi apparatus, glycogen, lipid droplets, lysosomes	Vascular system	Rich vasculature (12% of the islet)	Role	Fat absorption
Biliary system	18% of liver volume	Exocrine tissue	Production of pancreatic digestive enzymes	Midintestine	Narrow, folded 3 times on itself and measures 120–140 µm in diameter
Bile canaliculi	Presence of microvilli on the surface. Diameter = 2.22 µm	Acinar cell	Polyhedral, 8–10 µm in size, surrounding a central acinar duct	Composition	More goblet cells than in the intestinal bulb. Enterocytes have shorter microvilli (2-3 µm long, 115 nm in diameter)
Bile ducts	Intrahepatic, and extrahepatic ducts	Organelles	Zymogen granules (2.30 µm), nucleus, ER, mitochondria	Role	Proteins absorption
Vascular system	17% of liver volume	Pancreatic system	Main pancreatic ducts through the middle of the pancreas head	Posterior intestine	Narrow and measures 80–90 µm in diameter
Endothelial cells	Fenestrated, average diameter = 130 nm.			Composition	Rare or no microvilli
				Role	Osmoregulation