组织胚胎学课件 七年制英文医学班专用 中国医科大学 基础医学院 组胚 — 英文教学组

Chapter 14 Digestive gland

---small gland: fundis gland, small intestinal gland ---large gland: salivary gland, pancreas, liver

1. Salivary gland 1) General structure of exocrine gland ---Capsule: CT, which separate the parenchyma into lobules ---lobule:

① acinus: a. serous acinus: structure: pyramidal or cuboidal round basally-located N apical: zymogen granule-acidophilic basal: basophilic-RER, ribosome function: secret salivary amylase

b. mucous acinus: structure: pale-stained, slight-blue, flattened N against the basal membrane mucinogen granule Golgi, RER, mitochondria c. mixed acinus: several serous cell attached to mucous acinus – serous demilune

② duct: a. intercalated duct: simple squamous epi. simple cuboidal epi. connect with acinus

b. striated duct (secretory duct): intralobule simple columnar epi. : tall cell, acidophilic round N, located at apical part longitudinal striation: plasma membrane infolding c. interlobular duct and major duct : simple columnar epi. or pseudostratified ciliated columnar epi.

2) structural feature of each salivary gland a. parotid gland: -serous -long intercalated duct, short striated duct

b. submandibular gland: -mixed( mainly serous, less mucous and mixed) -short intercalated duct, long striated duct

c. sublingual gland: -mixed(mainly mucous, more serous and mixed) -more demilunes, no intercalated duct, under-developed striated duct

* granular convoluted tubule, GCT: ---a segment convoluted duct between intercalated duct and striated duct in submandibular gland ---epithelial cell: pyramidal in shaped, with large N apical cytoplasma: eosinophilic granules granules contain: i. growth factors-NGF, EGF,MGF, EGSF, EGF ii. homeostasis factors: renin, Kallikrein, CSF, ACF iii. digestive enzymes: amylase, ribonuclease, acid phosphatase iv. intracellular regulating factor

2. Pancreas ---capsule: CT, septa ---parenchyma: /exocrine pancreas /endocrine pancreas

1) exocrine pancreas ---acinus: serous *centroacinar cell: small, pale cell with round or ovoid N, derived from epithelial cell of intercalated duct ---duct: long intercalated duct ---function: secret pancreatic liquid 1-2L/D, PH Digestive enzymes: trypsinogen, chymotrypsinogen, amylase and lipase

2) endocrine pancreas( pancreas islet) , constitute about 1% of total pancreas volume um ---HE: cells arranged into cord with CT rich in fenestrated cap.

---EM: a. A cell: 20%. Large polygonal in shaped, peripheral- distributed EM: secretory G: large, nm, round with dense core function: secret glucogon - 29 amino acid residues protein ↓ glycogen→ glucose

b. B cell: 75%, small, centrally-distributed EM: secretory G: different diameter, nm with one or several dense core function: secret insulin - 51 amino-acid residues

c. D cell: 5%, ovoid, fusiform, peripheral-distributed, between A, B cells EM: -gap junction with A,B cell -secretory G: large, nm, low- density core function: secrete somatostatin to inhibit the secreting of A, B, PP cell

d. PP cell: EM: secrete granule: small, nm function: secrete pancreatic polypeptide to inhibit the secreting of pancreatic liquid, movement of viscera and contraction of gall bladder e. D 1 cell: 2-5%, peripheral, irregular EM: small, nm, function: secrete VIP(vasoactive intestinal peptide) f. C cell: undifferentiated cell

3. Liver ---largest, 2% of body weight ---capsule: DCT, insert into parenchyma to separate the parenchyma into hepatic lobule ---hepatic lobule ---portal area

1) hepatic lobule: basic structural unit mm long, 1 mm in across D ---polygonal prism( irregular) ---structure: central vein hepatic plate: radiating arranged hepatic sinusoid

① Central vein: small vein: endothelium + CT 45 um receive the blood from sinusoids

② Hepatic plates ---formed by single layer of hepatocytes a. hepatocyte: LM: polygonal, um eosinophilic N: -large, pale, round, centrally- located -1/4 binucleate

EM: mitochondria: , 20% total volume RER: involve in the synthesis of albumin, fibrinogen, clotting factor, lipoprotein and complement protein SER: contain enzymes- oxidoreductase (oxidase, reductase), hydrolase, transterase, synthetase, involve in the formation of bile and the metabolism of adipose, glucose and hormones

Golgi apparatus: involve in -formation of bile -process, condense and storage of proteins -formation of lysosome Lysosome: involve in phagocytosis activity and metabolism of bilirubin microbody: -round, um -contain catalase and peroxidase inclusions: glycogen, lipid droplet, pigment

b. bile canaliculus: ---cell membrane of adjacent hepatocytes depress to form a tubular system between hepatocytes

---structure: silver preparation: dark-brown colored network 0.5-1um Microvilli tight junction, desmosome

③ Hepatic sinusoid ---space between hepatic plates ---structure: LM: 9-12 um endothelial cell: fenestrated, gap, plasmalemmal vesicles RF cavity: -liver macrophage(Kupffer cell) -large granular lymphocyte: NK cell

EM: Perisinusoidal space: Disse space - narrow space between endothelial cell and hepatocytes 0.4 um width blood plasma microvilli RF fat-storing cell:

*fat-storing cell: -irregular, with processes -EM: large lipid droplets, RER, mito, Golgi -function: storage of vitamin A(E,K), synthesis of collagen

* The three kinds of different surfaces of hepatocytes ---face adjacent cell each other: 55% ---face the sinusoids: 35% ---form bile canaliculus: 10%

2) portal area ---areas(triangle-shaped or irregular-shaped) where adjacent hepatic lobules meet ---contains CT and several ducts

a. interlobular arteries: branches of hepatic A small A: endothelium layers of SM b. interlobular vein: branches of portal vein small vein: endothelium + less CT and single SM c. interlobular bile duct: simple cuboidal or low columnar epi.

3) Blood circulation of liver hepatic A →interlobular A →terminal hepatic arteriole portal V→interlobular V→terminal portal venule → hepatic sinusoid →central vein→sublobular V →hepatic V→inferior vena cava 4) Passage of bile ｛