GI/L Histology Flashcards

1
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LIP 1

  • mucosa = typical of mouth (stratified squamous non-keratinising epithelium - SSNKE)
  • @ margin, abrupt transer to skin (stratified squamous keratinising epithelium - SSKE)
  • connective tissue (sub-mucosa) - collage and elastin
  • deeper layers - glands and striated skeletal muscle (change shape of oral cavity)
  • small blood vessl @ sub-mucosa help keep moist
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2
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LIP 2: TRANSITION

SSNKE (lower) to SSKE (upper)

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3
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LIP 3

  • inner lip: SSNKE
  • small clumps of salivary tissue
  • sebaceous glands (Fordyce’s spots) open to surface rather than hair follicles
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4
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HAIR FOLLICLE

  • on keratinised surface of lip
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5
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TONGUE 1

  • SSNKE on ventral (lower) surface
  • SSKE on dorsal (upper) surface - constant abrasion
  • coarse multi-directional skeletal muscle bundles

extrinsic fibers - skeletal muscle inserted to lower jaw

intrinsic fibers - skeletal muscle inserted to fibrous connective tissue underlying mucosa

mixed sero-mucous salivary glands (SUBLINGUAL)

lymph nodules - particularly @ posterior 1/3 of tongue (linguinal tonsisl)

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6
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TONGUE - UPPER SURFACE

  • SSKE
  • connective tissue
  • 2 types of salivary glands
  • large bundles of striated muscle
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7
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TONGUE - SEROUS GLANDS

  • more pink staining (darker than mucous)
  • small serous salivary glands
  • acini - clusters of grapes
  • nucleus on base
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8
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MUCOUS GLANDS

  • small salivary mucus gland
  • michael palin = mucus pale*

mucus glands stain paler than serous!

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9
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PAPILLAE AND TASTE BUDS

  • dorsal tongue surface - complex folds = papillae

sweet (tip) / slaty (front/side) / sour (further back) / bitter (whole back)

filiform papillae (threadlike) - most common, tall, pointed - @ whole anterior 2/3

fungiform papillae (mushroom-like) @ tip and sides

  • @ lateral side fungiform papillae = pale-staining, spindle-shaped taste buds w/ nerves/synaptic vesicles

circumvallate papillae (V-shaped row) @ divide between anterior 2/3 and post. 1/3

this slide - 2 paler staining taste buds embedded in opposing sides of adjacent fungiform papillae

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10
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NERVES OF TONGUE

  • small nerves lying in sub-mucosa of tongue
  • supple close by taste buds
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11
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PAROTID SALIVARY GLAND (SEROUS ONLY)

  • striated duct (top left)
  • surrounded by serous acini
  • synthesise alpha-amylase
  • secreted via ducts to mouth
  • ducts can alter ionic concentrations
  1. branches of facial nerve pass through gland
  2. large lymph nodes embedded within gland

secretory cells - pyramidal, spherical nucleus, basal cytoplasm full of rER, apex contains prominent secretory granules (pink staining)

duct cells - simple cuboidal (stratified at distal end)

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12
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PAROTID GLAND 2

  • C (bottom) = nerve
  • D = large lymph node

inset - close up of lymph node

parotid saliva contains IgA (from plasma), combines with proteinous pieces so reaches intestine unmodified by amylase

striated duct - from invaginations, indicative of water reabsorption

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13
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SUBLINGUAL SALIVARY GLAND (MAINLY MUCUS)

  • pale staining secretory cells
  • darker staining duct w/ simple cuboidal epithelium
  • flattened oval nuclei to base of cells
  • branched tubular acinar glands
  • sticky mucus rich secretion

major constiuent - polysaccharide

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14
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PSNS (parasympathetic nervous system) GANGLION

  • PSNS ganglion
  • many nerve cell bodies
  • involved heavily in secretion regulation

this slide = sublingual

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15
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SUBMANDIBULAR SALIVARY GLANDS (MIXED)

  • well defined / globular
  • branched tubulo-acinar
  • interspersed with fat adipose
  • mixed secertion - part mucus, part enzyme rich

demi-lunes - serous cells form demi-lunes (half-moons) at closed ends of tubules

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16
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LYMPH NODULE WITHIN SUBMANDIBULAR GLAND

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17
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EPIGLOTTIS

  • @ posterior of tongue
  • boundary of oropharynx and laryngeal pharynx
  • mostly SSNKE
  • lower part posterior - pseudo-stratified columnar ciliated epithelium (respiratory)

contains:

  1. elastic cartilage plate
  2. lymph nodules (submucosa)
  3. salivary glands (submucosa)

Box A = buccal surface - faces mouth

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18
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EPIGLOTTIS 2

  • SSNKE
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19
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GI FORMATIVE 1

  • this is a tastebud surrounded by squamous epithelium
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20
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GI FORMATIVE 2

  • mucus acini
  • basally located nuclei
  • ducts lined by cuboidal/columnar epithelium

this is a sublingual gland

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21
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GI FORMATIVE 3

  • serous glands @ bottom
  • mucus glands @ top
  • this is mixed

therefore this is a submandibular gland

(mixed = submandibular)

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22
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GI FORMATIVE 4

  • this is purely serous (granules)

this is parotid gland

therefore contains branches of facial nerve

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23
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GI TRACT LAYERS (x4)

  1. mucosa - innermost. epithelium (folded), connective tissue (lamina propria - w/ lymphoid tissue), smooth muscle ring (muscularis mucosa)
  2. sub-mucosa - loose connective tissue, glands and lymphoid tissue, many blood vessels, meissner’s plexus (enteric nervous sytem)
  3. external muscle coat (muscularis externa)- 2 layers of smooth muscle - persistalis -auerbach’s plexus (enteric nervous system)
  4. serosa - simple squamous epithelium
24
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OSEOPHAGUS

mucosa:

  • SSNKE
  • thin lamina propria
  • narrow muscularis mucosa (thicker @ gastric end)

below diaphragm:

  • simple columnar epithelium (same as gastric region of stomach)
  • site of pathological change - Barrett’s oesophagus!

sub-mucosa: sero-mucous glands (lubrication), large thin-walled veins (@ distal end - oesophageal variscosities)

muscularis externa:

upper 1/3 = skeletal / middle 1/3 = mixed / lower 1/3 = smooth

25
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STOMACH

  • 4 regions: cardia/body/fundus/pyorus
  • cardia and body are histologically similar with respect to glands
  • muscosa thrown into folds (rugae)
  • simple columnar epithelium punctuated by gastric pits
  • muscularis externa is 3 layers thick - additional oblique fibers for churning

gastric mucosa scattered with pale-staining endocrine cells - serotonin, somatostatin, vasoactive intestinal peptide (VIP).

these regulate breakdown and delivery to duodenum

26
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GASTRIC GLANDS

  • tubular @ mucosa
  • fill lamina propria
  • 3 main cell types
    1. parietal (HCl + intrinsic factor [B12 absorpition])
    2. chief cells (digestive enzymes - pepsinogen, zymogen for pepsin)
    3. mucus neck cells (lubricant - acid resistant mucus)
  • full glands @ body and fundus
  • no parietal / chief @ cardia and pylorus
27
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STOMACH BODY - GASTRIC MUCOSA

  • simple columnar epithelium - produce acid resistant mucin
  • gastric pit invaginations (green arrows)
  • several tall, straight or brached glands to each pit
  • submucosa = loose connective tissue with abundant vessels
  • muscularis externa = 3 layers of smooth muscle

muscularis mucosa also contains elastic (black) to stop stomach collapse on empty

28
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PARIETAL (OXYNIC CELLS)

  • @ gastric glands of body/fundus
  • @ upper part of gland close to pits
  • globular - bright pink with H&E
  • cell surface invaginated (intracellular canaliculi) w/ many mitochondria (dark staining- grainy appearance)
  • rich in carbonic anhydrase

pH - 2

29
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CHIEF (ZYMOGENIC CELLS)

  • pyramidal @ deeper gland
  • cytoplasm - blue H&E - contains granules (pepsiogen/lipases)
  • @ body and fundus
  • close to muscularis mucosa

PEPSIN - affinity for collagen

30
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PYLORIC REGION

  • cardiac and pyloric glands are shorter
  • glands are coiled
  • mainly mucus neck cells
  • scattered with cells producing gastrin
31
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GASTRODUODENAL JUNCTION

32
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VILLI AND CRYPTS

  • intestinal lining - folds - plicae circularis (highest @ jejunum, lowest @ distal colon)
  • further SA increase - villi

villi - simple columnar epithelium (enterocytes and goblet cells). short life - but replaced by crypt production

contain - veule, arteriole, lacteal, smooth muscle (milks the villus)

venule and lacteal to liver

crypts of leiberkuhn - between villi, stem cell population, migrate to top and shaved off (takes 5 days)

33
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ENTEROCYTES

  • major absorptive cell
  • 300 short microvilli on apical surface - brush border
  • @ outer surface brush border = glycocalyx (enzymes) - filter most nutrients through this
  • water and glucose (some) via intracellular pathways

high concentrations of HEXOSE SUGARS mean brush border stains intensely by PAS

34
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DUODENUM

  • 12 inches, few plicae circularis
  • villi - broad and leaf like
  • few goblet cells
  • submucsoa conatins mucus secreting brunner’s glands - alkaline secretion neutralises CHYME

brunner’s gland bottom right

few pale staining goblet cells

long crypts

n.b. submucosal brunner’s glands not found in jejunum/ileum

inner circular layer thicker than outer longitudinal layer of muscularis externa

35
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DUODENUM 2

  • crypts form new enterocytes and goblet cells
  • dividing cells have very dark staining nuclei or sets of chromosomes
  • @ bottom of crypts = DIFFERENTIATED PANETH CELLS
  • secrete lysozyme - breakdown of bacterial cell walls
  • regulate flora of gut
  • bright pink cytoplasmic granules
36
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JEJUNUM

  • close-packed plicae circularis
  • many goblet cells
  • long narrow villi (finger-like)
  • short crypts
  • loose submucosa (almost detached from muscularis externa)
  • no brunner’s glands or peyer’s patches
  • lymph nodules at lamina propria, but do not penetrate submucosa
37
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ILEUM

  • final segment of small intestine, therefore fewer plicae and shorter villi (less absorption)
  • goblet cells increase towards distal end
  • large peyer’s patches @ submucosa (lymphoid tissue w/ lymphocytes)
  • Peyer’s patches erupt through muscularis mucosa to lamina propria
38
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ILEUM 2

  • serosa (simple squamous) on edge of longitudinal muscle
39
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VERMIFORM APPENDIX

  • from caecum
  • simple columnar epithelium
  • goblet cells
  • no villi
  • simple crypts
  • lamina propria and submucosa full of lymphoid tissue (declines w/ age)
  • no muscularis mucosa
  • muscularis externa present
  • transverse smooth muscle at muscularis externa = taenia colis - 3 longitudinal bands
  • fat filled
40
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APPENDIX 2

  • simple columnar epithelium
  • rudimentary crypts with few goblet cells
  • lamina propria and submucosa full of lymphoid tissue
41
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COLON

  • all segment similar histologically
  • little folding
  • no villi
  • mucosa contains close packed crypts with abundant goblet cells and enterocytes
  • restricted lamina propria (by crypts)
  • prominent muscularis mucosa
  • mucosa and sub-mucosa contain a lot of lymph - GALT (gut)
  • musuclaris externa - thickened inner circular layer, outer layer drawn into 3 longitudinal bands = taeniae coli

this slide - close packed crypts and abundant goblet cells

42
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RECTO-ANAL JUNCTION

  • rectum = similar to colon
  • simple columnar epithelium
  • anal canal - stratified squamous epithelium, keratinised at distal end (as lip)
  • submucosa was FAT, VEIN PLEXUS (anal varicosity)
  • smooth muscle of muscularis externa thickened and surrounded by STRIATED MUSCLE of EXTERNAL ANAL SPHINCTER
43
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RECTO-ANAL JUNCTION

  • box B - striated muscle of sphincter
  • box D - anal glands
44
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GI FORMATIVE 5

  • villous
  • sub-mucosa with Brunner’s glands
  • duodenal epithelium contains some lymphocytes between epithelium

DUODENUM

45
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GI FORMATIVE 6

  • all of this fits on a microscopic slide therefore not colon
  • flat mucosa with no villi
  • abundant lymphoid tissue in lamina propria and submucosa
  • lacks a muscularis mucosa
  • receives lod from superior mesenteric artery

VERMIFORM APPENDIX

46
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GI FORMATIVE 7

  • flat surface
  • no villi
  • numerous straight crypts
  • abundant goblet cells
  • prominent muscularis mucosa
  • stem cells at base of crypts

COLONIC MUCOSA

47
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LIVER

  • hepatic portal system receives nutrients
  • main cells - hepatocytes functions:
    1. creation/store energy as glycogen & fat
    2. synthesise plasma proteins
    3. de-amination of amino acids and production of urea
    4. uptake, synthesis, excretion of bilirubin and bile acids
    5. detox and inactivation of drugs by oxidation, methylation or conjugation
  • polygonal lobules of cells
  • each lobule with central vein and radiating hepatocytes (cords)
  • between cords = sinusoids (blood vessels) - bathe hepatocytes in mix of venous and arterial blood
  • blood drains from each lobule via central vein - hepatic
48
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LOBULE

  • cords of hepatocytes
  • sinusoids (wide, thin, fenestrated capillaries) = 70% portal vein blood, 30% portal artery blood
  • portal triads at corners of loules
  • arteriole (hepatic artery), venule (hepatic portal vein - nutrient rich blood), bile ductule
  • hepatocytes store: glycogen, trigylcerides
  • bile ductule = simple cuboidal epithelium

this slide - small muscular arteriole (top left), venule (bottom), bile ductule (top right, simple cuboidal)

hepatocytes secrete nile to extra-cellular bile canaliculi

hepatocytes replicate

49
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SINUSOIDS

  • wide, thin walled, fenestrated capillaries
  • endothelial cells interspersed with:
    1. kupffer cells - fixed macrophages
    2. ito cells - perisinusoidal cells (fat storing)
  • too thin to resolve
  • sit of meshwork of reitculin (collagen 3)
  • separated from heaptocyte cords by space of Disse (no blood cells here, but there is plasma) - albumin/fibrinogen synthesised at liver enters blood @ space of Disse

this slide - cords of hepatocytes with paler staining sinusoids between. nuclei of endothelial sinusoidal cells smaller and darker than that of hepatocytes.

50
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SINUSOIDAL MACROPHAGES

  • Kupffer cells in lining of endothelium
  • phagocytose blood borne pathogens
  • part production of bilirubin (taken up and excreted by hepatocytes)

n.b. demonstrate presence by uptake of coloured dye, contain particulate deposits

this slide - Kupffer cells have taken up blue/black ink. they line cords between pink-staining hepatocytes.

51
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HEPATOCYTE ULTRASTRUCTURE

  • GI = glycogen
  • Mi = mitochondria
  • N = nucleus
  • RER = rough endoplasmic reticulum

sinusoidal membrane contains transport mechanisms for pinocytotic release of macromolecules

canalicular membrane is target for bile discharge

well devloped rER - synthesis of plasma proteins

sER - inactivation of drugs (enzymes)

glycogen particule rosesstes and lipid droplets present

52
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GALLBLADDER

  • BILIARY TREE = ALL CUBOIDAL EPITHELIUM
  • smaller vessels = simple
  • distal end = stratified

gallbladder

  • simple columnar w/ poor brush border
  • adapated for water reabsorption (concentrating bile)
  • epithelium thrown into folds (not villi!)
  • large veins in walls
  • smoth muscle at outer surface
  • serosa visible at top (simple squamous)

n.b. contracts by CCK released from duodenum in response to fat from stomach

53
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EXOCRINE PANCREAS

  • exocrine = 98% of gland
  • serous (watery/enzyme rich)
  • digestive enzymes from same cell, secretion granules at upper part of cell
  • enzymes released as food enters duodenum
  • enzymes activated by alkaline environment of duodenum

stimulated by secretin to release ALKALINE FLUID from CENTRO-ACINAR and small duct cells

this slide - centro-acinar cells by green arrows

54
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PANCREAS

  • inset
    1. pacinian corpuscle - pressure sensor in pancreas (and skin)
    2. nerve plexus - with vagus nerve

also contains islets of langerhans (see SUGER)

55
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EXOCRINE PANCREAS DUCTS

  • each acinus has a narrow intercalated duct (ID)
  • IDs connect acinus to main duct (MD)
  • larger ducts -> 1/2 MDs that enter duodenum with bile duct

SIMPLE CUBOIDAL EPITHELIUM (stratified at distal end, as GB)

n.b. duct cells produce most of the fluid in secretion

56
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PORTAL TRIAD