Gastrointestinal tract 2

Question 1

34. Tongue- filiform and fungiform papillae (HE)

Answer 1

• striated visceral muscle⇒ longitudinal, transversal, vertical
• non-keratinized stratified squamous epithelium
• mucosal papilla: epithelium + lamina propria
• Filiform papillae:
  
  • most numerous
  • conical shape
  • slightly keratinized epithelium
  • no taste buds
• Fungiform papillae:
  
  • taste buds
• lamina propria: highly vascular
• aponeurosis linguae: dense fibrous CT in deep lamina propria

Question 2

50. Tongue- foliate papillae (HE)

Answer 2

• foliate papilla:
  
  • mucosal ridges
  • non-keratinized/ slightly keratinized stratified squamous epithelium
  • secondary papillae- CT epithelium interface
  • taste buds + taste pores
• von Ebner’s glands:
  
  • under base of papilla
  • serous glands
  • empty their product in inter papillary sulci
  • excretory ducts- startified cuboidal epithelium
• aponeurosis linguae ⇒ deeper lamina propria

Question 3

Taste buds

Answer 3

CONTENT:

• supporting cells
• gustatory cells
• rod shaped cells
• basal cells

Question 4

49. Tongue - circumvallate papillae (HE)

Answer 4

• Circumvallate papillae:
  
  • in front of sulcus terminalis
  • amount: 8-12
  • slightly project out from mucosal surface but encircled by deep cleft
  • non-keratinized stratified squamous epithelium
  • taste buds
• von Ebner’s glands
  
  • serous glands
  • drain product into base of cleft

Question 5

54. Tooth (unstained)

Answer 5

• Crown, neck, root
• Enamel (brown)
  
  • crown
  • enamel⇒ prisms of calcium hydroxyapatite crystals, extend to dentino-enamel junction, parallel
  • interprismatic material⇒ binds prisms together
  • dark lines of Retzius⇒ due to directional changes in growth of prisms
  • devoid of collagen
• Cementum
  
  • from neck to root
  • thin, hard calcified substance
  • thicker around apical part of root
  • small lacunae + canaliculi (black bc of air)
• Dentine
  
  • beneath enamel and cementum, encloses pulp cavity
  • 70% hydroxyapatite, 20%organic material, 10%water
  • dentine tubules
  • Tomes’ fibers: between dentine tubules, originally occupied by cytoplasmic processes of odontoblasts
  • hyaline layer: outermost layer of root dentine
  • granular layer of Tomes

Question 6

55. Tooth development (Mallory stain)

Answer 6

• development starts in week 6
• basal layer of oral epith. proliferates into ectomesenchyme of jaws ⇒ condensation of ectomesenchyme ⇒ tooth bud
• bud stage⇒ early cap stage ⇒ late cap stage ⇒ bell stage

Question 7

Mallory stain

Answer 7

• common use: CT
• nuclei: RED
• cytoplasm: PALE RED
• red blood cells: ORANGE
• collagen fibers: DEEP BLUE
• cartilage: BLUE
• bone matrix: BLUE
• muscle fibers: RED

Question 8

Late cap stage

Answer 8

• extoderm grows around ectomesenchyme ⇒ peripheral cells cuboidal
• ectodermal structure ⇒ enamel organ
• ectomesenchymal aggregation ⇒ dental papilla
• cells in contact with dental papilla ⇒ columnar ⇒ inner enamel epithelium
• outer cells cuboidal ⇒ external enamel epithelium
• mesenchyme condenses around enamel organ ⇒ dental sac

Question 9

Bell stage

Answer 9

• week 8
• edge of outer and inner enamel epithelia ⇒ cervical loop
• cells on inner enamel epithelium ⇒ ameloblasts ⇒ induce papillary ectomesenchymal cells to elongate + extend processes to basal lamina = odontoblasts
• odontoblasts secrete: dentine matrix
• dentine matrix induces ameloblasts to produce enamel matrix
• central polygonal cells of enamel organ ⇒ stellate shaped ⇒ stellate reticulum
• stratum intermedium: polygonal cells adjacent to inner enamel epithelium
• odontoblasts secrete predentine⇒ dentine
• around root the dental sac forms cement and periodontium