The extrinsic glands of the digestive system include the major salivary glands, the pancreas, and the liver, all of which are located outside the wall of the digestive tract. The major salivary glands consist of three pair of glands: the parotid, submandibular glands and sublingual glands.

Fig. 1 Submandibular gland : mixed gland Interlobula r septum parenchyma

Fig. 2 Submandibular gland(HE stain,high mag.) ① Mixed acinus ② Serous acinus ① ② serous demilune

Intercalated duct Fig.3 Submandibular gland(HE stain,high mag.) ① mucous acinus ② Serous acinus ① ②

Fig.4 Submandibular gland(HE stain,high mag.) ① Secretory duct ② Serous acinus ① ②

Fig.5 Submandibular gland (HE stain,high mag.) Intralobular duct

The pancreas can be divided into two portion: exocrine portion and endocrine portion. The exocrine portion is a serous, compound tubloacinar gland. The endocrine portion is called pancreatic islet( islet of Langerhans).

Fig. 6 Pancreas (HE stain, low mag.) ① pancreatic islet ② exocrine portion ① ② ①

Fig.7 Pancreas (HE stain, high mag.) centroacinar cells

Fig. 8 Pancreas(HE stain, high mag.) ① pancreatic islet ② exocrine portion ① ②

Fig. 9 A cell of pancreatic islet (TEM) ① nucleus ② secretory granule The cells secrete glucagon. ① ②

Fig. 10 B-cell of pancreas islet(TEM) ① nucleus ② secretory granule The B cells secrete insulin. ① ②

The liver is the biggest gland in the body. It can be divided into two main parts: hepatic lobule and portal area. The hepatic lobule includes five components :central vein, hepatic plate(cord), hepatic sinusoid, perisinusoidal space and bile canaliculi.

Hepatic lobule Portal areas Fig. 11 Liver of pig (HE stain, low mag.)

Central vein Hepatic cord Hepatic sinusoid Fig. 12 hepatic lobule (HE stain, high mag.)

Hepatocyte

Fat- storing cell

Fig. 13 Portal area of liver(HE stain, high mag.) ① interlobular artery ② interlobular vein ③ interlobular bile duct ① ② ③

Central vein Fig. 14 Liver of human (HE stain, low mag.)

Hepatic macrophage Fig. 15 Liver of mouse (trypan blue injected preparation, high mag.) Hepatic macrophage

Fig. 16 Hepatic macrophage in hepatic sinusoid (SEM)

bile canaliculus Central vein Fig. 17 liver(silver stain, low mag.) showing bile canaliculus

Fig. 18 liver (silver stain, high mag.) showing bile canaliculus bile canaliculus

Fig.19 gall bladder (HE, low mag.) plica Three layers : mucous membrane, muscularis and serosa.

Fig.20 gall bladder (HE, low mag.) Simple columnar epithelium