Salivary Gland Development

Question 1

Salivary glands develop through reciprocal interactions between

Answer 1

epithelium and underlying mesenchyme

Question 2

3 processes of salivary gland organogenesis

Answer 2

positional information, morphogenesis, differentiation

Question 3

Assembly of multicellular salivary glands involves

Answer 3

cell shape changes, cell migration, axis elongation during duct formation and changes on tissue specific gene expression

Question 4

Branching morphogenesis in mammalian salivary glands require

Answer 4

reciprocal epithelium-mesenchyme interactions that result in repetitive clefting, new bud formation and branching

Question 5

Organs that develop by branching morphogenesis through reciprocal epithelial-mesenchyme tissue interactions (6)

Answer 5

tooth, hair, kidney, lung, mammary gland, salivary gland

Question 6

Where do salivary glands originate from? (submandibular, parotid, sublingual)

Answer 6

primitive gut endoderm (submandibular)

ectoderm-derived surface epithelium (parotid and sublingual)

Question 7

During branching morphogenesis, progenitor cells undergo these processes to form specialized salivary cell types

Answer 7

maintenance, proliferation, lineage commitment, differentiation

Question 8

Salivary glands comprised of these cell types

Answer 8

epithelial, myoepithelial, mesenchymal, neuronal, endothelial.

These cell types must interact for normal function.

Question 9

Function of myoepithleial cells in salivary glands

Answer 9

Facilitates secretion of saliva (stimulated by neuronal cells)

Question 10

k19 cells

Answer 10

Cells that will eventually will be in middle of duct forming lumen of duct

Question 11

Fibronectin formed by what cell types?

Answer 11

Epithelial and mesenchymal

Question 12

How does fibronectin specify shape of salivary epithelium?

Answer 12

Accumulation of fibronectin (via secretion in epithelium and deposited by mesenchymal compartment) specifies cleft, lowest concentration of fibronectin at bud region

Question 13

Laminin

Answer 13

• interacts with integrins in basal region
• regulate developmental processes
• follows formation of new ducts

Question 14

FGF signalling

Answer 14

• required for branching morphogenesis

- inhibition of Fgfr1 expression decreases branching morphogenesis (probably more detail than needed)

Question 15

Inner bud cells differentiate to form ___, while outer bud cells differentiate to form ___ during salivary gland development

Answer 15

Inner differentiate to form ductal structures, outer differentiate to form acinar cells.

Question 16

F actin important in which aspect of salivary gland development?

Answer 16

Duct development. Collaborates with ZO-1 to elongate ductal axis for duct extension

Question 17

ZO-1

Answer 17

distrubuted asymmetrically to set up polarity in apical domains in inner bud cells on duct forming regions of the bud

Question 18

Parasympathetic innervation regulates _____

Answer 18

tubulogenesis in developing salivary gland and further development of duct formation

Question 19

tubulogenesis

Answer 19

formation of ductal structures during branching morphogenesis, involving assembly of cells into a tubular network

Question 20

microlumen

Answer 20

A small lumen which is formed during tubulogenesis, which will eventually fuse with other microlumens to form a single large lumen

Question 21

K19+ cells

Answer 21

Proliferate and condense to form microlumens

Question 22

Vasoactive intestinal peptide (VIP)

Answer 22

regulates key steps in tubulogenesis:

• duct elongation through proliferation
• fusion of microlumens

Once lumen is formed, required for lumen expansion

Question 23

NRTN

Answer 23

important in bringing neuronal cell into involvement of salivary gland formation

Question 24

E-cadherin

Answer 24

• cell-cell adhesion molecule
• required for survival of differentiating duct cells and for maintenance of lumens
• tumor suppressor: suppresses abnormal growth

Question 25

Polarity of cells maintained by

Answer 25

Maintained by junctional proteins in developing tissues

Question 26

Inhibition of E-cadherin would cause:

Answer 26

dilated and abnormal lumen formation

Question 27

Hippo signalling pathway

Answer 27

interacts with E-cadherin cell-cell adhesion receptor to drive normal duct formation

key regulator/suppressor of many diseases (like cancer).

Question 28

TAZ and YAP

Answer 28

• transcription factors in Hippo pathway
• inappropriate nuclear localization can cause abnormal expression of genes (cause pro-growth, etc)
• increase expression during SMG development
• inhibition of YAP prevents branching morphogenesis

Question 29

Sjogren’s Syndrome

Answer 29

• disregulatoin of cell polarity, E-cadherin junctions and nuclear localization of YAP seen in diseased salivary glands
• autoimmune disease
• impaired salivary flow and fatigue
• increased levels of vimentin, aSMA, CTGF, fibronectin

Question 30

Fibrosis

Answer 30

Leads to stiffening of tissues and loss of normal body functions. Often seen in head and neck radiation therapy when patients cannot swallow properly afterwards