Chapter 4: Developmental Biology of the Skin Flashcards Preview

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Flashcards in Chapter 4: Developmental Biology of the Skin Deck (46)
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1

____________________ are immune cells that reside predominantly in the epidermis, and internalize and present potentially harmful antigens encountered in the environment to initiate an immune response.

Langerhans cells

2

___ is a transcription factor with multiple isoforms that is perhaps the central regulator of epithelial identity.

p63

3

____ is very important to hair follicle formation and function.

Shh

4

______
It is critically important for the development of appendages

EDAR (ectodysplasin A receptor)

5

BMP (bone morphogenic protein) ligands are a family of ligands that bind BMP receptors and, among other functions, regulate _______________

hair follicle cycling and growth

6

____________ transcription factor family is important in large-scale body patterning

HOX (homeobox)

7

The cell that composes the majority of the epidermis is the ___________, so named because the structural protein keratin is abundant in that cell

keratinocyte

8

While keratins are the protein most abundant in the epidermis, _________ are the most abundant protein in the dermis.

collagens

9

The primary cell of the dermis is the _________, which produces collagens but has a large repertoire of other functions

fibroblast

10

The third trimester runs from weeks ________ and is when most development completes, including the formation of the _________ from the skin whose function is thought to lubricate for the pas- sage through the birth canal

26 to 40
vernix caseosa

11

The morula divides to form a more complicated structure called a ______, which has 2 main parts
1) ______
2) ______

blastula
trophoblast (placenta)
inner cell mass (embryo)

12

The _________ forms eventually the epidermis and melanocytes, but also the nervous system

ectoderm

13

Neural crest development initiates during the _______ of fetal life when the ectoderm forms the neural plate within it

third week

14

Although they mostly contribute to the axial skeleton and muscles, early somite fibroblasts are also precursors for ___________

Many of these fibroblasts—especially from body locations such as the back—originate from the dorsolateral portions of the somite, which is also called the _______________.

dermal fibroblasts

dermatomyotome

15

Non–melanocyte-related diseases of neural crest migration include _________________________ where 22q11.2 deletion results in defects in cardiac, craniofacial, and endocrine organs, among others.1

DiGeorge syndrome

16

Skin forming begins when the ectoderm converts to a single layer known as the _____________—a cuboidal, mitotically active and undifferentiated layer.
It expresses the gene _____, which is vital for epidermal differentiation and also corrupted in the EEC syndrome.

germinativum
p63

17

Genes that control periderm formation include _____, _____, and IKKα, likely partially through the nuclear factor kappa B (NF-κB) pathway.

Recent evidence suggests it is also a protective layer that prevents pathologic adhesions to adjacent epithelium, so that lack of periderm formation leads to the _________________

SFN, IRF6

human cocoon syndrome

18

The dermis is formed from the mesodermal layer of the embryo; consequently, it is referred to as ___________

mesenchyme

19

Whereas fibroblasts from the ventral body are thought to derive from _______________, fibroblasts from the head are thought to develop more from ____________________, and those, for example, of back skin are more likely to develop from _________ (and more specifically dermatomyotomes).

lateral plate mesoderm
neural crest precursors
somites

20

In particular, fibroblasts are programmed with a specific combination of ________, which, even after culturing of fibroblasts, are retained to specify,

HOX genes

21

The upper dermal fibroblast progenitor (PDGFRa+, _______, Dlk−, ____) become dermal papillae (a ball of fibroblasts that control hair keratinocytes), arrector pili muscle (muscle attached to hair that causes goosebumps), and the fibroblast of the upper dermis termed ______________.

Blimp1+
Irig1+
papillary fibroblasts

22

The lower dermal fibroblast progenitor (PDGFRa+, Blimp1−, Dlk1+) give rise to not only adipocytes but to the _________ (lower density and biased _______ over col- lagen III production).

reticular fibroblasts
collagen I

23

Even though peroxisome- proliferator-activated receptor γ (PPARγ) is an important transcription factor for both white and brown adipose development, ______ appears to be uniquely important for brown adipose development

Prdm16

24

Hallmark clinical syndromes of defects in mesenchymal development include focal dermal hypoplasia or ________ caused by mutations in the PORC gene,

Goltz syndrome

25

Analogous clinical syndromes for adipose tissue include the lipodystrophy syndromes such as Berardinelli-Seip where a lack of adipose development occurs from defects in the lipid synthesizing ________

AGPAT2 gene

26

Melanocytes can be detected by the _________ estimated gestational age (EGA) in human epidermis

eighth week

27

Their (melanocyte) precursor is a __________ progenitor, which also can differentiate into glial cells in addition to melanocytes.

SOX10-positive

28

These precursor cells actually can lose expression of MITF and KIT to revert to a ___________—the adult melanocyte stem cells—that live in the _________ bulge stem cell compartment

melanoblast
hair follicle

29

In addition to populating hair follicles, melanoblasts are thought to home to sweat glands where they might contribute to ___________.
These melanocyte stem cells supply interfollicular melanocytes as well, most dramatically during ultraviolet light therapy for patients with ________

acral melanomas
vitiligo

30

dermal melanocytes are thought to persist after birth in several locations, including the dorsa of the hands and feet, the _________, and the scalp. These areas are clinically important because they are also common sites for ________.

sacrum/buttocks
blue nevi