OCB02-2019 Flashcards by Sophie Chung

What shape are the cells of the intercalated salivary ducts?

Cuboidal

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What may the role of intercalated duct cells be?

Precursors for acini and striated duct cells

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What is important in maintaining osmotic differences during saliva formation?

Tight junctions

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What developmental tissue are the major salivary glands derived from?

Oral ectoderm

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What developmental tissue are the minor salivary glands derived from?

Oral ectoderm and endoderm

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How might ectodermal dysplasia affect salivary glands?

Abnormality of ectoderm so loss of major glands but only some minor glands

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What kind of interactions are essential in tooth and salivary gland development?

Epithelial-mesenchyme interactions

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When is the initial bud stage for the human parotid?

6 weeks i.u.

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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

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Knockout of which genes can affect the initial bud stage?

FGF-10, FGFR2b in epithelium

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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

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Which MMP creates space during the pseudoglandular stage?

MMP14

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What happens if you knockout EGFR at the pseudoglandular stage?

Reduced number of terminal buds

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If you pair parotid mesenchyme with sublingual epithelium, what branching pattern will develop?

Parotid branching

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What role does FGF1 have in the pseudoglandular stage?

Elongation of buds

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What role does FGF2 have in the pseudoglandular stage?

Proliferation of end parts/acini

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What gene is important for epithelial expansion during the pseudoglandular stage?

SHH

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BMPs antagonise the action of what group of molecules?

FGFs (growth in general)

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What are BMPs important for during the pseudoglandular stage?

Forming clefts/separations between cell types

Maximise branching to increase surface area for saliva production

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When is the canalicular stage for the human parotid?

~10 weeks i.u.

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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

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Which factors/receptors are important in the canalicular stage?

BMP7

Grain-head transcription factor

Retinoic acid receptors

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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)