At gastrulation, cells divide into 3 layers: what are they?
ectoderm then divides into_________(2 layers)
Neuroectoderm (neural crest and neural tube)
epidermis is derived from________
Formed from Ectoderm
what are the five layers of the skin?
at week 6, what is developed in the epidermis?
at week 8, what is happening in the development of the epidermis?
Intermediate layer and Basal layer
defects at week 8 of skin development lead to which condition?
Defects at this point lead to Ectodermal Dysplasia
what defects are seen in ectodermal dysplasia?
Defects in hair, teeth, bone, skin
by mid-third trimester, describe development of the skin. which protein is expressed and what about the cell formation of the cell envelope? what do defects at mid 3rd trimester lead to?
By Mid 3rd Trimester: Terminally differentiated epidermal layers similar to adult skin
Filaggrin expressed and the cornified cell envelope formed
Defects at this point lead to some of the ichthyoses
which conditoin? mutation in what causes this?
what are the three specialized cells in the epidermis?
melanocytes (produce and distribute melanin)
langerhan cells (
merkle cells (specialized cell, neural type)
know: where do melanocytes originate?
where do melanocytes migrate to?
eye(choroid, iris, ciliary body, retnia)
skin(epdiermeis and hair follicles)
KNOW: Origin/migration/survival- defect leads to _________________
Origin/migration/survival- defect leads to patches of depigmentation where no migration took place (eg Waardenburg Syndrome, Piebaldism)
KNOW: melanin synthesis defects lead to _____________
Melanin synthesis- defect leads to defective production of melanin (albinism)
KNOW:Melanosome formation and movement- defect leads to ___________
Melanosome formation and movement- defect leads to pigment dilution
Chediak-Higashi, Hermansky Pudlak Syndrome
cause: Defective melanocyte mutation leads to patches of depigmentation
what causes it?
cause: Different gene populations in one individual
Melanocytes develop along lines of Blaschko
Pigmentary mosaicism seen as linear streaks or whorls
X-linked conditions often follow lines of blaschko due to lyonization(x-incactivation)
what causes it
cause: Waardenberg Syndrome
Defective survival of melanocytes leads to patches of depigmentation
Enteric ganglion cells also affected (also from neural crest)
what causes it?
cause: Due to ineffective production of melanin
Melanocytes are present, but there is no melanin
Different genes lead to different phenotypes
condition: Hermansky Pudlak and Chediak Higashi Syndrome
cause: Ineffective transfer of melanosomes to keratinocytes lead to pigmentary dilution (silver hue).
what is affected: May affect other cells where lysosomal trafficking is important (Neutrophils, Neurons, Platelets)
mode of inheritance?
progression of disease?
which three defects are present?
which gender is it fatal in utero in?
condition: incontientia pigmenti
XLD: x-linked dominant
progression of disease: blaschkoid vesicles-->verrucous-->hyperpigmented-->hypopigmented lesions
defects: ocular, dental, CNS
FATAL in utero in males (females can survie b/c of lyonization)
KNOW: dermis is dervied from _________
Derived from both ectoderm and mesoderm
dermis: By 12 weeks EGA, _____________is fully functional
___________function of skin not fully developed until 3 weeks after birth
By 12 weeks EGA, dermal-epidermal junction is fully functional
Barrier function of skin not fully developed until 3 weeks after birth
Body surface area to weight ratio is ________ times that of adults
infants have increase ___________of topical medicines
Premature infants have increased_________loss
Infant Body surface area to weight ratio is five times that of adults
Increased percutaneous absorption of topical medicines
Premature infants have increased transepidermal water loss (TEWL)
considerations in prematurity:
1. stratum cornenum of premature babies compared to adults and full term infants?
2. How long does it take premature babies to have competent barrier function?
3. increased ________ loss compared to full-term infants
4. 3 ways premature infants differ from regular infants
1. thinner stratum corneum than adults and full-term infants
2. can take longer than 3 weeks for competent barrier function
3. increased Transepidermal water loss compared to full-term infants
4. increased risk of infections, increased percutaneous absorption of topical medicines, and decreased temp and fluid regulation
what is it?
what is its function?
what is it composed of?(3)
Protective membrane present at birth
Mechanical barrier in utero
Composed of epithelial cells, sebaceous secretions, and shed lanugo hair
physiologic changes in new born:
what is it?
what is it accentuated with?
how does it resolve?
Accentuated with temperature decrease
Resolves with re-warming
neonatal desquamation, sucking blisters, lanugo, sebaceous gland hyperplasia, and milia are all _______
physiologic changes in newborn