OCB02-2019 Flashcards
What shape are the cells of the intercalated salivary ducts?
Cuboidal
What may the role of intercalated duct cells be?
Precursors for acini and striated duct cells
What is important in maintaining osmotic differences during saliva formation?
Tight junctions
What developmental tissue are the major salivary glands derived from?
Oral ectoderm
What developmental tissue are the minor salivary glands derived from?
Oral ectoderm and endoderm
How might ectodermal dysplasia affect salivary glands?
Abnormality of ectoderm so loss of major glands but only some minor glands
What kind of interactions are essential in tooth and salivary gland development?
Epithelial-mesenchyme interactions
When is the initial bud stage for the human parotid?
6 weeks i.u.
Describe the initial bud stage of salivary gland development.
6 weeks i.u.
Thickening of oral cavity ectoderm to form an epithelial placode
Reciprocal interactions with mesenchyme form condensing mesenchyme or “papilla” around placode as placode expands
Knockout of which genes can affect the initial bud stage?
FGF-10, FGFR2b in epithelium
Describe the pseudoglandular stage of salivary gland development.
Further proliferation of bud via epithelial-mesenchyme interactions
No duct yet
MMP14 creates space in mesenchyme for epithelium to grow into
SHH important for epithelial expansion
EGF, FGF, MMP determine branching - mesenchyme patterns the branching
Which MMP creates space during the pseudoglandular stage?
MMP14
What happens if you knockout EGFR at the pseudoglandular stage?
Reduced number of terminal buds
If you pair parotid mesenchyme with sublingual epithelium, what branching pattern will develop?
Parotid branching
What role does FGF1 have in the pseudoglandular stage?
Elongation of buds
What role does FGF2 have in the pseudoglandular stage?
Proliferation of end parts/acini
What gene is important for epithelial expansion during the pseudoglandular stage?
SHH
BMPs antagonise the action of what group of molecules?
FGFs (growth in general)
What are BMPs important for during the pseudoglandular stage?
Forming clefts/separations between cell types
Maximise branching to increase surface area for saliva production
When is the canalicular stage for the human parotid?
~10 weeks i.u.
Describe the canalicular stage of salivary gland development.
~10 weeks i.u.
Formation of lumen/ducts by apoptosis of central cells and controlled growth/proliferation
Which factors/receptors are important in the canalicular stage?
BMP7
Grain-head transcription factor
Retinoic acid receptors
What can failure of the canalicular stage lead to?
Can cause cysts/ranulas (swellings under mucosa)
Especially in minor glands
When is the terminal bud stage for the human parotid?
~16 weeks i.u.
Describe the terminal bud stage of salivary gland development.
~16 weeks i.u.
Type 1 cells (along branches) will form striated ducts
Type 3 cells (at ends of branches) will form acini
Myoepithelial cells now apparent
At what stage do myoepithelial cells appear during salivary gland development and how could you visualise this?
Terminal bud stage
Stain actin
When is the perinatal stage for the human parotid?
~36 weeks i.u.
Describe the perinatal stage of salivary gland development.
~36 weeks i.u.
Until now, nerves have been growing alongside the tree
Development and integration of nerves with acini - PS first causes saliva secretion (then sympathetic)
Which nerves integrate with acini first (perinatal stage)?
Parasympathetic
What is the effect of parasympathetic nerves not integrating with acini before birth?
Reduced acinar and myoepithelial maturation
How can you see the salivary protein profile of a gland?
Northern blot (measures mRNA)
In rodents, when is submandibular gland protein B (SMGB) present?
During embryonic development
In rodents, when is amylase, DNAse 1 and parotid secretory protein (PSP) present?
After development of glands
What is found in a human baby’s saliva?
Most adult proteins
Mostly IgD and some IgA (shifts during first year) and albumin
What is the main difference between human and rodent salivary gland development?
Human salivary glands almost fully developed before birth
Rodent glands still developing post-natally (hence perinatal stage)
What factors can influence the salivary glands?
Tooth eruption - PDL mechanoreceptors increase innervation to glands
Weaning - solid food means chewing^
Puberty - hormones
Menopause - hormones can cause atrophy
Why is decreased salivary function associated with old age?
Increased fibrosis and fat deposits in glands as you age
Polypharmacy
What tissue are the parotid glands associated with?
Lymph nodes
What type of acini are found in parotid tissue and how does it stain with H&E?
Serous
Purple/dark (secretory granules)
In which gland are serous demilunes found?
Submandibular gland
What type of acini are found in sublingual tissue and how does it stain with H&E?
Mucous acini
Pale-staining
Which gland has very few striated duct cells? Why might this be?
Sublingual gland
Very thick saliva so shorter distance to travel to mouth is required
Are striated ducts found in intra- or interlobular glandular tissue?
Intralobular
Which gland has many plasma cells present? What does this mean for the saliva produced?
Sublingual gland
Lots of IgA in this saliva so protective
Which major gland are the minor salivary glands most similar to? How is the saliva similar?
Sublingual glands
Lots of IgA and mucin
What are stromal cells? Give an example.
Cells found outside of the glandular/acini tissue
Adipocytes, lymphocytes/plasma cells
Where are the arteries and veins found in a salivary gland?
Interlobular connective tissue
Are collecting and excretory ducts found in intra- or interlobular glandular tissue?
Interlobular
Which type of autonomic nerve tends to be larger in cross-section in salivary glands?
Parasympathetic
Which type of autonomic nerve tends to be myelinated in salivary glands?
Parasympathetic
Which type of autonomic nerve tends to follow blood vessels in salivary glands?
Sympathetic
Which duct in salivary glands has the smallest lumen?
Intercalated ducts
Which side of the acini are myoepithelial cells found?
Basal
Which stain can be used to visualise mucins and elastin?
Alcian blue
Why does the Alcian blue stain show mucins so strongly?
Mucins are very negatively charged as they are large and highly glycosylated
Alcian blue is positively charged
Which stain can be used to show basement membranes?
PAS stain (periodic acid-Schiff)
