OCB02-1011 Tooth morphogenesis Flashcards
Which genes determine the type of tooth that forms?
The expression of homebox genes in the mesenchyme into which the tooth germ invaginates
How is the enamel knot initiated?
The primary knot is induced at the bud stage of tooth development by signals from the mesenchyme
The PEK expresses a number of signalling molecules
Fgf4 and Shh stimulate growth and proliferation of the dental epithelium
The enamel knot expresses growth factors but does not express the receptors so cannot respond to its own signal
This leads to high proliferation on the outside of the enamel knot and low proliferation within the enamel knot. The result is a folding of the dental epithelium
What stimulates the death of cells in the enamel knot?
Bmp4 stimulates cell death leading to the loss of the enamel knot and silencing of this signalling centre
What would occur if there was not apoptosis of the enamel knot?
The tooth would grow forever
Which tooth develops SEKs and TEKs?
molars
What determines the height of the cups?
The timings of the initiation of secondary enamel knots
How is the number of cusps on a tooth increases?
Stimulating multiple signalling pathways
What signalling molecules are uses to increase the number of enamel knots?
Activiin
Eda
Shh
What factors determine whether there will be a cusp of carabelli or not?
If tooth is large and if the cusps are closer together there is additional space for the cusp of carabelli
How will growing a tooth in the presence of alveolar bone affect the tooth?
It will constrain the size of the tooth
What do defects in the PEK lead to?
Smaller or misshapen enamel knot, resulting in the reduced number of cusps
What do mutations in the Eda gene lead to?
HED
What does overexpression of Eda result in?
formation of additional cusps
