Flashcards in Chapter 4: Developmental Biology of the Skin Deck (46)
____________________ 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.
___ is a transcription factor with multiple isoforms that is perhaps the central regulator of epithelial identity.
____ is very important to hair follicle formation and function.
It is critically important for the development of appendages
EDAR (ectodysplasin A receptor)
BMP (bone morphogenic protein) ligands are a family of ligands that bind BMP receptors and, among other functions, regulate _______________
hair follicle cycling and growth
____________ transcription factor family is important in large-scale body patterning
The cell that composes the majority of the epidermis is the ___________, so named because the structural protein keratin is abundant in that cell
While keratins are the protein most abundant in the epidermis, _________ are the most abundant protein in the dermis.
The primary cell of the dermis is the _________, which produces collagens but has a large repertoire of other functions
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
The morula divides to form a more complicated structure called a ______, which has 2 main parts
inner cell mass (embryo)
The _________ forms eventually the epidermis and melanocytes, but also the nervous system
Neural crest development initiates during the _______ of fetal life when the ectoderm forms the neural plate within it
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 _______________.
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
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.
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 _________________
human cocoon syndrome
The dermis is formed from the mesodermal layer of the embryo; consequently, it is referred to as ___________
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
In particular, fibroblasts are programmed with a specific combination of ________, which, even after culturing of fibroblasts, are retained to specify,
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 ______________.
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).
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
Hallmark clinical syndromes of defects in mesenchymal development include focal dermal hypoplasia or ________ caused by mutations in the PORC gene,
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 ________
Melanocytes can be detected by the _________ estimated gestational age (EGA) in human epidermis
Their (melanocyte) precursor is a __________ progenitor, which also can differentiate into glial cells in addition to melanocytes.
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
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 ________