Expansion
Hepatic lobules with portal triads, and pancreatic acini with islets
Expansion
Liver
- Classic lobule: hexagonal, with a central vein at the centre and portal triads at the corners
- Portal triad: hepatic artery branch, portal vein branch and bile ductule, plus lymphatics and nerves
- Sinusoids lined by fenestrated endothelium with Kupffer cells (resident macrophages) and stellate (Ito) cells storing vitamin A and becoming fibrogenic in disease
- Space of Disse between endothelium and hepatocytes
- Bile flows in the opposite direction to blood, from canaliculi towards the portal triad
Pancreas
- Exocrine: serous acini with basophilic basal cytoplasm and apical zymogen granules; centroacinar cells are unique to the pancreas and mark the start of the duct
- Endocrine: islets of Langerhans, about 1 to 2 per cent of the gland, appearing as pale islands. Beta cells (insulin, about 70 per cent, central), alpha (glucagon, peripheral), delta (somatostatin), PP cells
Islets are most numerous in the tail, which is why distal pancreatectomy affects glucose control more than proximal resection.