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Slide 1

  • Lip
  • Exterior surface and interior surface
  • Red margin is the vermilion border
  • Outside surface of the lip is distinguished by hair follicles, with sebaceous glands surrounding them
    • Stratified squamous keratinised
    • Lots of collagen and fat, and circular sphincter around the mouth: orbicularis oris (there is orbicularis occuli around the eye)
  • Inside of the lip
    • Stratified squamous non keratinised
    • Seromucous glands (Labial salivary glands)
    • Mucous is pale staining, serous is dark staining
    • Large duct lined by stratified cuboidal epithelium (not a blood vessel, which are lined by endothelium/simple squamous)
    • Lots of blood vessels as well
  • Vermilion border - is where lips are very red on the outer margin, very vascular area (where lipstick goes)
  • He could ask us to draw a lip and label it
  • Nerve fascicles:
    • Can see light pink wavy nerve fascicles (bundles) cut in cross section

Slide 2

  • Infant lip
  • Hair follicles
  • Orbicularis oris muscle
  • Seromucous labial salivary glands - mostly serous in the infant
  • Inside of the lip (mucous membrane, lined by stratified squamous nonkeratinising)
  • Red margin
  • Infant has more serous secretions than
  • Can see ducts from seromucous glands to the surface (simple cuboidal epithelium)

Slide 3

  • Soft palate
  • Two surfaces: 1) Stratified squamous slightly-keratinising 2) Pseudostratified columnar ciliated with goblet cells (goblet cells are very clear, like white freckles)
  • Between the surfaces, palatal salivary glands, producing mucous
  • Ducts
  • Interlacing striated muscle fibres (skeletal muscle)
  • Hard palate, bone - showing bone marrow
  • Palatine tonsil to the left and top, with lots of B cells (making antibody)

Slide 4

  • Lingual tonsil
  • Lingual tonsils are the dark purple blobs under the epithelium over the root of the tongue
  • Interlacing skeletal muscle
  • Indentation of the epithelium, called crypts (bacteria can get caught up in the crypt, and encounter the B lymphocytes of the lingual tonsil)
  • Stratified squamous epithelium (partially keratinising)
  • Lymphoid nodules are the dense blobs within the lingual tonsils
  • Mucoserous glands are in between the muscle (mainly mucous, but there are also serous ones)
  • Some mucous alveoli (aka acini) have serous demilunes
    • Always this arrangement: mucous acinus (pale) with a serous demilune (dark)
  • Fat

Slide 5

  • Circumvallate papilla
  • Circumvallate papilla - large papilla with taste buds in the lateral wall. There is a moat on the side of the papilla. Food goes down the moat in a semisolid state. There are little pores with the nerve hanging out of them, and this triggers a nerve impulse that heads to the gustatory centre
    • Taste is about protection against food that is off (like smell)
  • Epithelium of the tongue is stratified squamous with some keratin
  • Von Ebner's glands are the dark purple glands that produce a serous solution (making the saliva watery)
    • Classification: compound tubular alveolar gland
  • Can see ducts of serous acini that feed into the moat
  • Pink is collagen, and there is also striated (skeletal) muscle running in all directions (interlaced
  • Can see a lymphoid follicle (not encapsulated, so not a lymph node)

Slide 6

  • Tongue from a rabbit
  • Foliate papillae (not well developed in humans)
  • Can see taste buds with taste pores
  • Stratified squamous nonkeratinising epithelium
  • Blue is collagen, red is skeletal muscle (in various directions)
  • Glands - von Ebner's glands (serous secreting)
  • Nerve fascicles (peripheral nerves), blood vessels
  • Note that von Ebner's (serous) glands are more prevalent at the front of the tongue than the back (mucous). Mucous is slippery for eating.

Slide 7

  • Submandibular salivary glands <-- very important; visible on Dr Lazer's drawings
  • Lobes separated by collagen, then more collagen separating these into lobules (septae)
  • Dark acini are serous (watery solution)
  • Light acini are mucus (mucoid solution)
  • Mucous acini with a serous demilune (pale with a dark cap)
  • Submandibular gland classification: compound tubular alveolar gland
    • Both serous and mucus
  • Secretions are pushed out of intercalated ducts (small ducts from acini out to larger ducts)
  • From the intercalated ducts, you go to striated ducts (or intralobular ducts).
  • (Necklace of cuboidal epithelium)
  • Bigger ducts lying between lobules are interlobular ducts
  • From there we get bigger ducts, called lobar ducts
  • CT stroma
  • Simple cuboidal epithelium lines the ducts

Slide 8

  • Sublingual salivary glands - mixed, mostly mucus
  • Post-mortem degeneration
  • Classification: compound tubular alveolar, mixed
  • Majority is mucous, with some serous demilunes
  • Interlobar ducts are large ones between the lobes
  • Striated ducts are the larger ones when you zoom in to acinus level
  • Intercalated ducts are harder to find, small ducts leading to individual acini

Slide 9

  • Parotid gland - a serous gland
  • Classification: compound tubular alveolar gland
  • Serous acini (not mucus)
  • Ducts experienced lot of degeneration due to postmortem degeneration and shrinkage
  • Collagen septae
  • Zymogen granules - red dots within the acini. These are precursors to the enzymes (tylin and salivary amylase).
  • Lymph node capsule (collagen around it)
  • Large nerve could possibly be the facial nerve (CN XII) that runs through the parotid

Slide 10

  • Human oesophagus, cut in cross section
  • Layers:
    • Epithelium: stratified squamous nonkeratinised
    • Below that is lamina propria
    • Muscle: muscularis mucosa
      • NB:Mucosa = {epithelium, LP, muscularis mucosa}
    • Below that we have the submucosa (blood vessels, fat, collagen, nerves)
    • Muscularis externa
      • Note distinction between the smooth muscle (fusiform) and the skeletal muscle (striated).
      • Inner circular muscle (relative to the anatomy) (cut here in a longitudinal section - relative to the slide)
      • Outer longitudinal muscle (relative to anatomy) (cut here in a transverse section - relative to the slide)
      • This pattern continues through out the GIT
      • Both of the layers (inner circular and outer longitudenal) contain both smooth and skeletal muscle
  • Oesophagus: upper 1/3 (100% skeletal muscle), middle 1/3 (where the slide is, 50% skeletal, 50% smooth), lower 1/3 (100% smooth muscle, near the stomach)

Slide 11

  • Cardiooesophageal junction
  • Between oesophagus and stomach
  • Layers:
    • Epithelium: Moving between stratified squamous nonkeratinised to simple columnar (which covers most of the GIT)
      • Very sharp transition
    • Muscularis mucosa:Bottom of oesophagus is smooth muscle, which we can see here in 2 directions
    • Lamina propria
    • Muscularis externa
  • Not villi in stomach, but gastric pits (which sometimes go way down into the cardiac glands
  • Large folds are rugae
  • Stomach still has muscularis mucosa. Also has cardiac glands. Then submucosa with blood vessels.
  • Frothy pink mucus on top of epithelial cells
  • Dark artefacts: fold in the tissue
  • Role of muscularis mucosa: churning food (local movements). Further down in the GIT it is involved in tugging on villi (drinking the soup).
  • Myenteric (Auerbach's) nerve plexus is in muscularis externae (peristalsis)
  • Submucosal (Meissner's) nerve plexus is in muscularis mucosae (more local movements)

Slide 12

  • Stomach fundus
  • Folds: rugae
  • Mucosa:
    • Epithelium: simple columnar
    • LP
    • Can see strips of muscularis mucosa
  • Submucosa: collagen, nerves, fat
  • Extensive muscularis externa
    • In the stomach you have oblique, longitudinal and circular - agitation/churning food (assisted by rugae, pepsin, HCl). This is not present anywhere else in the GIT
  • Frothy pink mucus on surface
  • Gastric pits - some deeper than others
  • Gastric glands (bases of pits. Classification: simple branched tubular)
    • Parietal cell (fried eggs) - make HCl
    • Chief cells (dark purple) - pepsinogen (zymogen, converted to pepsin)
    • Mucus neck cell - in the base of the gastric pit. The epithelial cells also make mucus (protective layer from the acid)
  • Can see nerve fascicles as part of the Meissner's plexus (scattered in the collagen)

Slide 13

  • Pyloro-duodenal junction
  • No shift in epithelium
  • Duodenum on the left
    • Epithelium: Have villi (and microvilli, tiny) - no change in epithelium, but now have villi (fingers, which have goblet cells (white freckles) in them)
      • Lacteal: lymph ducts living inside villus (takes fat away in lymphatic system)
    • Lamina propria glands (glands of Lieberkuhn/intestinal glands; of the mucosa) - these are dark staining
    • Muscularis mucosa
    • Submucosa: Brunner's glands (unique to duodenum; in submucosa) - mucus secreting (alkaline; protecting duodenum from acid, no protective layer from acid) - these glands are light-staining
      • Brunner's glands are defined by being deep to the muscularis mucosa
    • Muscularis externae: inner circular, outer longitudinal, in between there is collagen and Auerbach's plexus (parasympathetic for segmentation and peristalsis)
    • Nodular lymphoid tissue
  • Stomach on the right
    • Pyloric sphincter (big ball of muscle)
    • Deep pyloric pits (very deep gastric pits)
    • Gastric glands
  • This part of the duodenum is retroperitoneal, so is covered by tunica adventitia (collagen, blood vessels, fat, nerves) and is not tunica serosa
  • Paneth cells also exist in intestinal crypts, but you can't see them in this slide

Make sure you can draw and label all these for the exam.