Download The esophagus = oesophagus

Digestive tube General plan of digestive tube From esophagus to lower end of the anal canal, the alimentary canal has the form of a fibromuscular tube The wall of the tube is made up of four basic layers (from inner to outer side) I. The mucosa = inner most layer = called mucous membrane composed of: 1. A lining epithelium It perform different function: a. Mainly protection esophagus stomach b. Secretory – stomach, intestine c. Absorptive intestine. The epithelium play a role in contribute to the external of the surface of the gut by presence of numerous fold, plica circularis, villi and microvilli. 2. Lamina propria A layer of connective tissue rich in reticular fibers, lymphoid tissue & play a role in immunological response 3. A thin layer of muscularis mucosa (smooth muscle) that marks the boundary between mucosa and submucosa. Contraction of the muscularis mucosa are important for local mixing of intestinal contents. Basically inner circular + outer longitudinal arrangement of smooth muscle bundles. II. Submucosa  This a layer of areolar (loose) connective tissue.  It is rich in blood vessels, lymph vessels, nerves + nodules. Meissner plexus near its junction with the inner circular muscle.

III. Muscularis Eterna Usually: it is composed of two layers of Smooth muscle inner circular outer longitudinal with some exception

The two layers are separated by C.T containing myenteric nerve plexuses that initiate peristaltic contraction. Exception: - Upper part of esophagus smooth muscle replaced by skeletal striated muscle. - In stomach extra muscle is added. - In the colon outer layer is gathered into three longitudinal bands Taenia coli. The adventitia or serosa: is the outer most layer of connective tissue. If its covered by serosa or peritoneal covering serosa. If is not covered by serosa or peritoneal covering Adventitia such as esophagus and rectum.

The esophagus = oesophagus It is a tube approximately 25 cm long transmit swallowed material from oropharynx to the stomach by rapid peristalsis. Anatomy: Its wall constitute the usual 4 layers:

Histologically: The wall is formed of the following layers: Mucosa a - Epithelium - Str. squ. Epith. Non keratinized (protective type) - Show several longitudinal folds b- Lamina propria =  Finger like projections may present like dermal papillae  Contains tubuloalveolar mucous glands c- Muscularis mucosa Mainly constitutes of longitudinal smooth muscle fiber very preminent in the lower half, with delicate elastic fiber. Submucosa - Connective tissue with dense collagenous and elastic fiber that is extremely plastic and resilient. - Oesophageal glands - branched tubuloalveolar gland. The acini contain mucous secreting cells / some serous secretory cells contain lysosomes. - Duct passes through mucosa to the lumen lubricate the esophageal lumen -It is present mainly lower half & esophageal cardiac glands. Muscularis Externa o Two components

inner circular outer longitudinal. o The upper third of esophagus, these are striated muscle. o Middle third of esophagus mixed and replaced by smooth muscle. o Lower third; it is replaced by smooth muscle.

They are supplied by autonomic nerve (plexus) include vagus, thoracic sympathetic trunk. These plexus present in between muscularis externa and in the submucosa. Swallowing start voluntary then occur automatically

Blue Histology (School of Anatomy and Human Biology - The University of Western Australia)

The stomach The stomach is responsible for storage and digestion of food. In the distal part of the stomach the solid mass of food transformed into chyme. Food mixed with pepsin, gastric juice, mucous + gastric intrinsic factor ( need for B12). Mucosa a- Epithelium  Type: Simple columnar mucous secreting cells.  The epithelium dips into the underlying lamina propria to forms a wall of depression called gastric pits. These pits extend for variable distance in the depth of the mucosa. Gastric glands open into these gastric pits. In addition there are longitudinal folds or ridges of the mucosa called rugae prominent in contraction Smooth out in relation or distention.  The epithelial cells are characterized by presence of an apical mucous cap. That stained with PAS. This cap is formed by secretion of mucous and pathing all the surface epithelium and act as a barrier. The mucous or the cap provide protection against acid contents of the stomach.  This barrier can be damaged by: - infection (bacterial heterobacter pylori. - Alcohol. - Aspirin , voltarin, Brufen = anti inflammatory decrease prostaglandin Increase gastric secretion by stress or anxiety ulceration Ulcer could be superficial to mucosa or deep.

brone to gastric

The surface epithelium has very high turnover rate, renewed every 3 days.

Lamina propria - Give support to the epithelium and contain lymphoid tissue - Give support to the glands that open into the pits. It is condensed with gastric glands Three types of glands can be described: (1) Gastric (fundic) or body = same. (2) Cardiac. (3) Pyloric. These gland are simple branched tubular. Lie at right angle to the mucosa. They open into gastric pits. Each pit receives opening of several glands. (1) Gastric gland = fundic  Have the general feature of gastric glands.  They are most important secretors of gastric juice.  Four cell types are located within the gland.  Chief cell, parietal, mucous neck cells, enteroendocrine cells. a. Chief = zymogenic = peptic cells - Site: numerous at the basal parts = lower part or third of the gland - Secretion: Pepsinogen: inactive precursor of pepsine. Pepsinogen protinase pepsine or stimulated by PH = 2

cholinergic stimulation (vagus) hormonal secretion - Shape  Cuboidal: low columnar shape  Basophilic cells have characteristic of protein secreting cells.  Bears small microvilli , basally located nucleus.  RER, ribosomes + secretory granules in the upper part. b. Parietal cells = oxyntic cells. Site:

Numerous in the upper half of the glands (neck + base) and present singly or wedged between peptic cells.

They are called oxyntic because stain strongly with eosin: red = deep esonophilic cells.

Mucosa of the stomach

Wall of the fundic stomach Copyright© 2000 Oklahoma State University College of Veterinary Medicine

Tunica muscosa of the fundic stomach Copyright© 2000 Oklahoma State University College of Veterinary Medicine

Micrograph of gastric glands in the stomach

Copyright© 2000 Oklahoma State University College of Veterinary Medicine

Shape: Ovoid or polyhedral cells with large central nucleus The apical cell membrane shows several invaginations into the cytoplasm producing tortuous intracellular canaliculi. They are called intracellular or secretory canaliculus These canaliculi lined by microvilli They have large numerous mitochondria S + RER limited, small golgi. Secretion  Hcl production hydrochloric acid. PH = 0.9 – 2  Secrete gastric intrinsic factor (GIF) which bind with vit. B12 and enhance its absorption in intestine. Secretion stimulate by gastrin, histamine + nerve stimuli Decrease B12 absorption + absence of G.I.F lead to: pernicious anemia. Pernicious anemia is called macromic macrocytic anemia Reduced intrinsic factor also can be caused by ulcers due to destruction of cells – antiacid – zentac, tegument block attachment of histamine to receptors in gastric cells: lead to decrease acid production c. Mucous neck cells Site: neck of the gland or upper part. Shape: - There are large cells with clear cytoplasm, the nucleus is flat and pushed to the periphery. - They stain with PAS.

Secretion: the mucus secreted by these cells differs from that secreted by mucous cells lining the surface of the gastric mucosa.

d. Argentaffin or enteroendocrine cells (DNES) = Diffuse Neuro Endocrine System (13 types all over) Small cells, has silver staining properties.  They are also known APUD = Amine precursor uptake + decarboxylate  Present in large variety of organ diffuse neuro endocrine system.  Resemble protein producing cells.  Located mainly in the base of the gland. e.g. gastrin gastric mobility HCL Somatostatin inhibit gastrin HCL Glucagons blood sugar Histamin capillary permeability HCL Serotin vasoconstrictor. e. Stem cells Cardiac glands  Present near the opening of the oesophagus.  Gastric pits are shallow.  Simple branched tubular.  Secret mucous – seromucous neck gland  Few APUD Pyloric glands  Present in the pyloric region predominant cell tubular coiled muco-neck gland.  Gastric pits are deep and occupy ⅔ of the depth of mucosa.  They more branched + highly coiled tubular.  No chief or few parietal cells present in cardiac (few PAUP) or pyloric glands (mainly mucous neck glands.  Muscularis mucosa – smooth muscle inner circular outer longitudinal + outer circular  Submucosa – same of oesophagus.

Muscularis Externa Three layers of smooth muscle: 1- inner oblique 2- Middle circular 3- Outer longitudinal. Circular fiber thickened in pyloric region. Adventitia Role of prostaglandin Prostaglandin protects lining epithelium + local circulation Increase blood flow Will facilitate release of ions from lamina propria. Polypeptide inhibits HCL production Asprin + brufen are anti prostaglandin.

Small intestine The wall of small intestine typically forms of 4 layers The mucous membrane The surface area of the mucous membrane (mucosa) is extensive (to allow adequate absorption). This accomplished by presence of the following: (all increase the surface area of S.I. by a factor of 400 – 600). 1. Plica circulares = valves of kercking. They are circular folds of mucosa and a core of submucosa, it extends about one half to ⅔ around the circumference of the lumen. Increase surface area of S.I. by factor of 2

2. Villi = finger like projections of mucosa that extend into luminal lumen, it reaches about 1.5 mm in duodenum 0.5 in ileum. Intestinal villi = villus  They are finger or leaf like projections of a surface epithelium surround core of lamina propria.  They gave the intestine its velvety appearance.  The center of the villus or the core contain an excretion of lamina propria with a central lymphatic vessels (lacteal) and a network of fenestrated capillaries. They increase surface area of S.I. by a factor of (10) Duodeneum villi are broader taller + numerous Jejenum narrow shorter + sparsest. Ileum sparsest, shorter + narrower Presence of numerous depression or crypts invade lamina propria, extend almost to muscularis mucosa. They are branched tubular glands 3. Microvilli The entorocytes apical surface presence numerous microvilli several thousand / cells. They give the apical surface its striated appearance, so called striated or brush border increase surface area by a factor of 20 .

Mucosa Epithelium of the villi

lined = simple columnar epithelium with goblet cells. L.P m.m

Three cell types form the covering of the villi (1) Columnar absorptive cells = most numerous = enterocytes They are tall columnar cells with oval round nuclei (basally situated). Their apical surface has a brush border = striated border due to microvilli. The microvilli of plasma membrane are covered by glycoprotein filaments ( surface coat). Function  Protection from proteolytic + mucolytic enzymes  Provide binding sites from specific substances that are to be absorbed.  Microvilli cell membrane also contains enzymes need for absorption.  Absorptive material lamina propria The cells are rich in endosomes, SER, RER, GA (2) Goblet cells = mucous secreting cells o They are flask shaped cells with peripheral flat nucleus. o They secret mucous to lubricate and protect epithelium Their number is smallest in duodenum increases forward ileum till large intestine. (3) Argentaffin cells = Enteroendocrine cells = hormonal secreting cells. Argentaffin = argyrophilic cells = because they stain with silver. o They are present in stomach, S.I, L.I, liver & pancreas o They are particularly prominent in the pyloric of the stomach & in the duodenum of S.I. (they may also present in respiratory system). o They are belong to APUD system (amine precursor uptake & decarboxyl) i.e they can take up precursors of amines & decarboxylate to them. o There are at least 3 different types of enteroendocrine cell types, the cytoplasm of these cells has well develop rER, GA.

o The secretory vesicles are small & membrane bound (toward the base or lamina propria and apical nucleus).

e.g. motilim neurotensin

increase intestinal motility decrease smooth muscle contractility.

Some of their peptide hormone present in CNS + PNS so collectively called diffuse neuroendocrine system (DNES). M cells = follicular epithelial cells, which are attenuated columnar Squamous opposite them, the regions where lymphoid nodules abut epithelium to trap antigen.

Blue Histology (School of Anatomy and Human Biology - The University of Western Australia)

II. Epithelium lining the crypts Simple tubular or simple branched tubular. In addition to three cells type present in the villi, there are two additional cell types: columnar + goblet cells mainly in upper parts of the glands. 1. undifferentiated stem cells = regenerative cells. Location: base of the crypts – they undergo mitosis do replace he cells that shed from the tips of the villi. (turn over – 5 -7 day) they have many ribosomes. They have electron – lucent basally oval located nucleus (heterochromatin) 2. Paneth cells Location: base of the crypts  They have apical, eosinophilic granules (abundance).  They are large, pyramidal in shape.  Long lived.  These secretory granules contain lysosome (antibacterial agent).  EM: Well developed GA, RER and numerous mitochondria, the apical secretory granules are homogenous. 1. Enteroendocrine cells II. Lamina ropria Fits the space between the crypts and forms the cores of the villi. Contents = lacteal (central lymph vessels), lymphocytes, macrophages, plasma cells (seen IgA), esinophils, loose C.T, lymphatic nodules is present solitary or as peyer’s patches. III. Muscularis mucosa = MM Composed of inner circular + outer longitudinal. The inner fibers extend into the core of the villus and surround the lacteal.

Submucosa It is composed of dense irregular C.T. with rich lymphatic & vascular supply. Contents: parasympathetic plexus = Meissner’s plexus. In duodenum characterized by presence of Brunner’s glands. Brunner’s gland = branched tubuloalveolar glands – resemble mucous acini due to pierce mm open into the base of crypt.

They secret mucous, alkaline fluid in response to parasympathetic stimuli. This fluid helps to neutralize or buffer acid content of stomach. Also these glands manufactyre urogastrine = human epidermal growth factor. It inhibits HCL production & amplilify the rate of mitotic activity in epithelial cells. Muscularis externa It is arranged as inner circular & outer longitudinal smooth muscle, they are separated by C.T. containing myenteric (Auerbachs) plexus. Adventitia = serosa it is formed of : Loose C.T lined extremely by mesothelium Serosa is lining all the intestine except first part of duodenum and lower end of rectum. N.B. Adventitia no peritoneal covering. Appendix  It has four layers of digestive tube  It has small lumen. Mucosa = epithelium

Simple columnar epithelium with high No. of goblet cells. Lamina propria lymphoid tissue + extend to submucosa M.M

Mucosa has crypts but no villi Cell population = simple columnar cells (enterocyte) with microvilli, goblet cells, paneth cells, argentaffin + basal undifferentiated cells. Submucosa Muscularis externa Invested by serosa Appendicitis = inflammation of appendix Peritonitis.

Small intestine: Mucosa

Small intestine: Villi : www.siumed.edu/~dking2/erg/GI020b.htm

fever, nausea, vomiting

Jejunum, basic layers with plica (cross section)

Jejunum, crypts : www.siumed.edu/~dking2/erg/GI020b.htm

Duodenum, basic layers (cross section)

Intestine, muscularis externa : www.siumed.edu/~dking2/erg/GI020b.htm

The large intestine: colon Function - Absorption of water & minerals - Converting the food residue into semisolid feces Typical  There is no plica circularis  No villi  Microvilli are shorter.  Intestinal crypts are deep.  Mucosa is rich in goblet mucous secreting cells & lack paneth cells, few enteroendocrine  All layers are similar to S.I.  Solitary lymphatic nodules scattered in the L.P & extend to submucosa.  The outer longitudinal layer of muscularis externa is recognize into three thick longitudinal bands teniae coli up to the rectum where muscularis retains its typical arrangement.  Serosa display numerous fat filled pouched appendices epiploicae Rectum has fewer crypts but deep rectum join the anus. There is large venous plexus in the lamina propria + submucosa In the submucosa sebaceous glands, sweat glands. Rectum inner circular internal anal sphincter, outer continue as fibroelastic sheath Anus ext. anal sphincter skeletal muscle. Malabsorption

multiple disease cause malabsorption

Enteritis: irritation of colonic mucosa. Cholera toxin - production of intestinal fluid 10L/day electrolytes hypovolemic shock.

loss of

Colon, mucosa

Colon, mucosa and submucosa : www.siumed.edu/~dking2/erg/GI020b.htm

Colon, mucosa, submucosa, and muscularis

Appendix : www.siumed.edu/~dking2/erg/GI020b.htm

Liver Is the largest glandular tissue in the body It has both exocrine & endocrine function Exocrine secrets bile into duodenum Endocrine synthesis some materials directly into the blood. e.g. albumen 90% of blood protein form by liver. Lipoprotein, α and β globulines, prothrombine fibronectine. It consists of stroma of C.T. and parenchyma of liver cells. Stroma Capsule: The liver is surrounded by a capsule of fibrous C.T. called Glisson’s capsule, it is covered partly by mesothelium (peritoneum) C.T trabeculae: The C.T capsule sends C.T trabeculae within the substances of the liver and divided into hepatic lobules. They are very thin in normal condition. In cirrhosis or fibrosis they thickened. Parenchyma or structural organization of the liver The primary cellular constitution of the liver is the hepatocytes, it account for about 80% of cellular constitution. The hepatocytes arranged into plates or laminae which branch and anastomose in the hepatic lobules. There are three (3) ways of describing the liver in term of functional unit: (1) Classic hepatic lobule. (2) Portal lobule. (3) Liver acinus. Portal lobule present between 3 classical hepatic lobule by lines draw between 3 central vein. Liver acinus = is a diamond shaped. It is smallest functional unit. It is composed of liver substance comprises from two adjacent classical lobules.

Classical hepatic lobule It is appeared as hexagonal or pentagonal in cross section. It is consisting of stacks or plates of hepatocytes which branch and anastomose. The plates or the cords radiating from the central vein. These plates or cords separated by blood sinusoids. The plates or cords commonly formed of 2 or more rows of hepatocytes. At the angle of the lobule are the portal areas = portal canals = loose stromal C.T having portal triads. Including : a. A branch of hepatic artery. H.A b. A branch of portal vein P.V c. A branch of hepatic bile duct. There is also collagen fibers, few hepatic and nerves Central vein sublobular veins drain into hepatic veins I.V.C inferior vena cava. Portal vein through portahepatis branches within the liver have typical structure of vein . Its lumen usually larger than the artery associated with it. The hepatic artery has typical structure of medium size arteries with thick muscular wall and smaller lumen. The direction of blood will pass from peripherally of lobule P.V + hepatic artery Terminate in the sinusoids drain into central vein. (hepatic artery may terminate directly sinusoids or into p.v. The bile will pass from central of lobule bile duct hepatic duct common bile duct. Hepatocytes They constitute 80% of cell population of the liver They are polyhedral cells with central nucleus. 65% mononucleated. 35% binucleated It is esinophilic stained (red pink) because cytoplasm is generally acidophilic. 20 – 30 um in each dimension.

It contains – numerous (400 – 1000mLcells) mitochondria, abundant SER, RER, well develop golgi apparatus, lysosomes. Glycogen (PAS) + lipids are usually present (may appear as irregular empty spaces during preparation). They are rich in perixosomes.

They are long lined cells, have regenerative capability. SER activity is stimulated by Phenobarbital, ethanol, chemothera steroid + progesterone. Hepatocytes have many surfaces which are modified in 3 main surfaces: 1. Surface facing the blood sinusoids, here the cell membrane possess irregular microvilli. The space between the hepatocytes + endothelial cell of blood sinusoids is called perisiniusoidal space. 2. Surface facing the bile canaliculi. 3. Surface line in contract between the two adjacent hepatocytes. Their cell membranes are tightly bound together by tight junction. Blood sinusoids = They are present between the cords or plates of hepatocytes. They are discontinuous types of capillaries, i.e. they are lined by simple squamous endothelial cells that have a discontinuous basal lamina. Hepatic sinusoids differ from other sinusoids that a second type, the Satellite sinusoidal macrophage or kupffer cell, it is irregular part of the vessel lining. Van- kupffer cell = fixed macrophages They are derived from monocytes. They are irregular cells with multible processes which arise from their cell wall to form pseudopodia. It is related to reticuloendothelial cell. They have rich in lysosomes. They have role in metabolism of hemoglobin + bilirubin.

The space of Disse: Perisinusoidal space. It lies between basal surfaces of hepatocytes + basal surface of endothelial cells + kupffer cells that line the sinusoids. Exchange of materials between blood + hepatocytes microvilli increase surface area by 6 times. Contents  Hepatocyte microvilli  Few reticular fibers.  No blood formed elements (blood cells) except in fetal liver or in chronic anemia in blood.  Blood plasma.  Excretion of lipoprotein & protein through this space blood.  Lipocyte or adipose cell. It is a primary site for storage of vit. A. Cod liver oil = fish liver oil medical source of vit. A.  Fiber in space early sign of fibrosis due disease or drugs or toxin.

Lobule of Pig Liver : www.siumed.edu/~dking2/erg/GI020b.htm

Pig Liver, overview

Liver, cords and sinusoids : www.siumed.edu/~dking2/erg/GI020b.htm

Liver, sinusoids with Kupffer cells

Gall Bladder : www.siumed.edu/~dking2/erg/GI020b.htm

Bile canaliculi Bile canaliculi are formed by a complete loop around four sides of idealized six- sided hepatocytes.  Diameter – 0.5 – 1.5 um.  Separated or isolated from rest of intercellular compartment by junctional complexes.  Short microvilli from adjacent surface of hepatocyte extend into canalicular lumen.  They can be seen by gold chloride a staining for the presence of alkaline phosphatase. Collecting into canal of hearing bile duct. Liver has a capability to rgenerate in rat 75% of organ is excaed regenerate to normal size.

Blue Histology (School of Anatomy and Human Biology - The University of Western Australia)

Pancreas It consists of 2 parts

exocrine endocrine

Pancreas performs two important functions: Exocrine = (1) Synthesis & release of digestive enzymes. Exocrine = (2) Synthesis & release of hormones that influence carbohydrate metabolism. The endocrine components of the pancreas islets of langerhanse The exocrine components secretory acini Exocrine pancreas  It is composed of compound tubuloacinar gland.  It produces 1200 ml of bicarbonate – rich fluid containing digestive enzymes.  The secretory actins is composed of pyramidal epithelial cells arranged around the terminus of an intralobular duct (intercalated duct). Acinar cell is pyramidal in shape rest on a basement membrane and are supported by reticular fibers. The nucleus is basally located.  The apical portion contains acidophilic granules = secretory granules = theory in sizes + its number after a meal.  The basal portion display basophilia rER EM = basal striation due to number of mitochondria well developed golgi apparatus, microtubules concentrated at the apex. Acinar cells (basal parts) have receptors for cholecystokinin. Duct system  It begins within the center of the acinus centroacinar cells (terminus of intercalated ducts) = it is composed of law cuboidal cells stained relative poorly to acinar cells.  Intercalated ducts join each other to form larger intralobular ducts (law columnar) several intralobular ducts. Converge to form interlobular ducts lobar main pancreatic duct common bile duct pupilla of voter.  Acute pancreatitis destruction of parenchyma.

 Pancreatic cancer 7% greater in smokers killer type 50% one year survival – male is greater than female. Acinar cells enzymes Duct system acinar : aqueous fluid rich in bicarbonate. Jaundice

obstructed Haemolytic Hepatic

Diabetes mellitus

conc. of conjugate both non-conjugate.

type I – insulin depend = jaundice Type II

Endocrine pancreas The endocrine cells of the pancreas are aggregated into spherical clusters known as islet of langerhans  





They are scattered among secretory acini They are composed of spherical conglomeration or cords of cells that are richly vascularized. There are about 1 million islets distributed throughout the human pancreas > in the tail. There are different cell types and are differentiated by their staining properties. (immuno cyto chemical processes). Depend on the properties of their cytoplasmic granules.

TYPE OF CELLS α cells (A)

Β cells

TYPE OF CELLS δ cells delta

DIAMETER

PLACE

PERCENTAGE SECRETION OF

GRANULE

Islets periphery Stain red with chrome alum haematoxylene Scattered all over by concentrated mainly in the center of islets Stain blue with chrome alum haematoxyline

PLACE

20%

Glucagons

250 nm

70 – 75%

Insulin 300 nm EM granule

PERCENTAGE SECRETION

DIAMETER OF FUNCTION GRANULE

Scattered throughout the islets

Scattered throughout the Islets Has no stainable granules

Blood Sugar

Blood glucose

5%

Clear cells Gorc

FUNCTION

1%

Somatostatin 350 nm

Gastrin

Contraction of smooth muscle of S+L intestin+ gall bladder

Stimulate Hcl by stomach

P-cells

P-1cell

Scattered throughout the Islets

1%

Pancreatic polypeptide

180 nm

Inhibit peristalsis & exocrine function of pancres

Vasoactive intestinal peptide Similar to glucagons Intestinal perstalis

Gall bladder It is a small pear-shaped organ situated on the inferior aspect of the liver. It has body + neck. 1. Mucosa = has mucosal folds. Epithelium o simple columnar with central elongated nucleus o Have short microvilli – attached to each other by tight junctions o There are two cells: clear cells, brush cells. Some contain mucous secreting granules. Lamina propria A vascularized loose C.T with elastic & collagen fibers. In the neck: the L.P contain tubuloalveolar glands produce mucous. No lymphatic vessels. M.m = no true muscularis mucosa or submucosa Muscularis externa Smooth muscle fibers which are randomly oriented some longitudinal, circular & oblique direction. These muscle are separated by interviewing collagenous fibromuscular coat, elastic & reticular fibers. External to M.E. is a thick layer of dense C.T. has autonomic nerve fibers reffered to it adventitia Un attached surface serosa.

Gall bladder stone Female, 49, fertile, fatty, fair 60% cholesterol, large, pale yellow pigment Has mucosa, muscularis propria and serosa on free surface; no muscularis mucosa or submucosa is present Mucosa: variable branching folds, more prominent if gallbladder not distended Surface epithelium: composed of single layer of uniform, tall columnar cells with basal nuclei, indistinct nucleoli, pale cytoplasm due to sulfomucins. Lamina propria: loose connective tissue with blood vessels, lymphatics, occasional chronic inflammatory cells (IgA secreting plasma cells), no neutrophils Muscular layer: circular, longitudinal and oblique smooth muscle fibers without distinct layers, resembles muscularis mucosa; adjacent to lamina propria without an intervening submucosa Adventitia: perimuscular connective tissue composed of collagen, elastic tissue, fat, vessels, lymphatics, nerves, paraganglia

Pancreas (200x) demonstrating serous nature of the digestive portion of this gland, as well as associated interlobular ducts. ©2003 Pearson Education, Inc., publishing as Benjamin Cummings