Skin Through the Ages Flashcards
At gastrulation, skin divides into what 3 layers:q
endoderm, mesoderm, ectoderm
Ectoderm then divides into ectoderm and neuroectoderm (neural crest and neural tube)
truth
What layers are formed from the ectoderm?
Stratum Basale, Stratum spinulosum, stratum granulosum, stratum lucidum (only on palms and soles), stratum corneum
At week 6 of life in utero…
bilayered epidermis (periderm and basal layer)
week 8
stratification begins, you get an intermediate layer and a basal layer
Ectodermal dysplasias are
defects in hair, teeth, bone, skin
Terminally differentiated epidermal layers exist by when
third trimester. Fillagrin is formed and the cell envelope is formed
Defects at the third trimester lead to
Ichythosis…due to filaggrin mutations
Melanocytes migrate from
neural crest
Melanocytes originate where
neural crest
What is piebaldism
defects in melanocyte migration lead to patches to of depigmentation where no migration takes place, its auto dominant
What is Wardenburg syndrome
Defective survival of melanocytes leads to depigmentation patches. Also affects enteric ganglion cells which can lead to megacolon
Hermansky Pudlack and Chediak Higashi syndrome
Ineffective transfer of melanosomes to keratinocytes leads to pigment dilution, this can also effect other processes that involve lysosome trafficking
Pigmentary mosaicism is seen as
linear streaks or whorls, these develop along lines of blashko
Incontinentia Pigmenti
x-linked dominant, failure in utero to males, some females can survive though they have ocular dental and CNS defects
Dermis is derived from
both ectoderm and mesoder
Dermal-Epiderma junction is not fully functional until>
12 weeks
Barrier function of the skin is not developed until 3 weeks after birth
truth
What is the body surface area to wt ration of babies versus adults
Five times greater
What is the significance of this increased body surface area to weight ratio?
It means that absorption of topical medicines is greater and that premature infants have increased transepidermal water loss