Lecture 17: Development of Integument Flashcards
What is cytodifferentiation?
Differentiation of a cell (becoming specialized)
What is histogenesis?
Development of tissues (involves different cell types)
What layer of skin is formed by the end of the first month and made of a single layer of ectodermal cells?
Periderm
When is the epidermis formed by and what layers does it consist of?
End of 3rd month.
Basal, intermediate, & superficial peridermal layers
What transcription factor initiates the formation of the 3 layered epidermis and where does it come from?
p63 from dermal mesenchyme
What inhibits p63 activation?
miR-203
What factors contribute to the formation of the basal layer of epidermis?
Keratins K5, K14, & K15
What factors contribute to the formation of the intermediate layer of epidermis?
Keratins K1 & K 10, loriccrin, & filaggrin
What allows the intermediate layer to form into the stratum spinosum and stratum granulosm?
Loss of integrins attached to basal lamina
What appears when the stratum granulosum is made?
Keratohyalin granules
The stratum corneum resembles flattened bags and the cells are interconnected via what protein?
Filaggrin
When do volar pads form on the palm and fingers?
Palm: 6.5 weeks
Fingers: 7.5 weeks
When do the volar pads begin to regress forming epidermal ridges?
10.5-11 weeks
Which epidermal cells undergo apoptosis?
Peridermal
What cells from the neural crest migrate into the dermis and then into the epidermis?
Melanobasts
What causes albinism?
Inability for melanocytes to convert tyrosine to melanin via the enzyme tyrosinase.