Deck 8: Development of the Skin and Its Derivatives

Question 1

During development,the keratinocytes of the various skin layers express different keratins and other intracellular proteins involved in the maturation of the skin.Transglutaminase 1 is one such protein.What is the human syndrome that can be caused by mutations in Transglutaminase 1?

A) Dowling-Meara EBS
B) Junctional epidermolysis bullosa
C) Bullous congenital ichthyosiform erythroderma
D) Lamellar ichthyosis
E) Incontinentia pigmenti
F) Hypohidrotic ectodermal dysplasia

Answer 1

D

Question 2

During which month do odontoblasts of the developing teeth start to produce predentin,which will then calcify to form dentin?

A) 2nd
B) 3rd
C) 4th
D) 5th
E) 7th

Answer 2

E

Question 3

Which phase of hair cell growth is the resting phase?

A) Anagen
B) Catagen
C) Exogen
D) Telogen

Answer 3

D

Question 4

Postnatally,hair is continually lost and replaced.In which region of the hair are the progenitors of the new hair cells located?

A) Inner root sheath
B) Bulge
C) Outer root sheath
D) Hair matrix

Question 5

What stage of hair development is affected in hypohidrotic ectodermal dysplasia?

A) Placode or hair germ
B) Hair peg
C) Bulbous hair peg
D) Keratinization of the hair shaft
E) Loss of the epithelial strand between the bulge and dermal papillae

Question 6

P63 (also known as Tumor protein p73-like [TP73L]) mutations affect development of the skin in a spectrum of syndromes that include ectrodactyly ectodermal dysplasia-cleft lip/palate.Which cell layer of the skin expresses P63?

A) Stratum granulosum
B) Stratum corneum
C) Stratum germinativum
D) Stratum spinosum

Question 7

The skin consists of several definitive layers.Which layer contains the proliferating cells that replenish the skin throughout life?

A) Stratum granulosum
B) Stratum corneum
C) Stratum germinativum
D) Stratum spinosum
E) Periderm

Question 8

The skin consists of several definitive layers that are characterized by the differential expression of different types of keratin involved in the maturation and differentiation of the skin.In which layer are the keratins K5 and K14 found?

A) Stratum granulosum
B) Stratum corneum
C) Stratum germinativum
D) Stratum spinosum
E) Periderm

Question 9

FOXN1 mutations in humans and mice result in the loss of hair.What stage of hair development is affected?

A) Placode or hair germ
B) Hair peg
C) Bulbous hair peg
D) Keratinization of the hair shaft
E) Loss of the epithelial strand between the bulge and dermal papillae

Question 10

Junctional epidermolysis bullosa is due to a mutation in which gene?

A) KRT5
B) PlakophIlin
C) Desmoglein 1
D) Laminin BETA3
E) KRT3

Question 11

Nevoid basal cell carcinoma or Gorlin syndrome predisposes individuals to basal cell carcinomas and is due to increased activity in a signaling pathway.Which signaling pathway is activated and which component of the pathway is usually mutated?

A) WNT, BETA-CATENIN
B) NOTCH, HES1
C) SHH, PTC1
D) BMP, NOGGIN

Question 12

Shh signaling is important for the development of the skin and many of its appendages.What is the main cellular mechanism by which Shh controls development of the ectodermal appendages?

A) Cell survival
B) Cell proliferation
C) Cell adhesion

Question 13

Mutations in the gene encoding the RUNX2 transcription factor result in cleidocranial dysplasia and also affect tooth development,causing which condition?

A) Hypodontia
B) Oligodontia
C) Dentinogenesis imperfecta
D) Amelogenesis imperfecta
E) Hyperdontia

Question 14

Vitamin A deficiency affects the development of the teeth.Which cell type and which structure is usually affected?

A) Ameloblasts producing the enamel
B) Odontoblasts producing the dentin
C) Inner cells of dental papillae, which give rise to the tooth pulp
D) Cells of the enamel knot that determine cusp number
E) Cementoblasts producing cementum in the root

Question 15

During embryonic development,both primary and secondary teeth develop,but the secondary teeth arrest their development.Growth and further development of the secondary teeth is later reinitiated during childhood.At what stage of tooth development are the secondary teeth arrested?

A) Bud stage
B) Cap stage
C) Bell stage

Question 16

Hypohidrotic ectodermal dysplasia can be life threatening due to a child's inability to thermoregulate,which can result in hyperpyrexia or hyperthermia.The gene mutations causing this syndrome have now been identified.Which signaling pathway is affected?

A) WNT
B) EDA/EDAR (TNF family)
C) SHH
D) FGF
E) BMP

Question 17

In X-linked syndromes,the loss of normal gene function in some of the skin progenitors can follow the lines of Blaschko.In which of the following syndromes would you expect this to occur?

A) Dowling-Meara EBS
B) Junctional epidermolysis bullosa
C) Bullous congenital ichthyosiform erythroderma
D) Lamellar ichthyosis
E) Incontinentia pigmenti
F) Hypohidrotic ectodermal dysplasia

Question 18

You suspect that a child may have Ehlers-Danlos syndrome.His symptoms include elastic hyperextensible skin,bruises,and atrophic scarring.The child is also double-jointed.If the diagnosis is correct,what cardiac abnormalities would you anticipate are also present?

A) Dilation of the aortic root
B) Shortening of the outflow tract
C) Abnormal differentiation of the myocardium
D) Defective formation of the cardiac valves
E) Abnormal remodeling of the aortic arches

Question 19

Sweat glands use which mechanism of secretion?

A) Apocrine
B) Eccrine
C) Holocrine