4 - Developmental Biology Flashcards
1
Q
Central cells of the epidermis
A
Keratinocytes
2
Q
Provides structural resiliency
A
Intermediate filament keratins
3
Q
Central cells of the dermis
A
Fibroblasts
4
Q
Extracellular secreted proteins; activate the frizzled receptors to eventually stabilize B-catenin
A
Wnt ligands
5
Q
Transcription factor; central regulator of epithelial identity
A
p63
6
Q
Extracellular secreted proteins; bind the smoothened receptor and eventually the Gli family of transcription factors
A
Shh ligands
7
Q
Bind the receptor Notch which initiates transcription and epidermal differentiation
A
Ligands Delta or Jagged
8
Q
Important in large-scale body patterning
A
HOX (homeobox) transcription factor family
9
Q
Protein most abundant in the epidermis
A
Keratin
10
Q
Most abundant protein in the dermis
A
Collagens
11
Q
When organogenesis has mostly completed
A
First trimester
Weeks 0-12
12
Q
Appearance of downy hair
A
Second trimester
Weeks 12-26
13
Q
When most development completes
A
Third trimester
Weeks 26-40
14
Q
Formation of the vernix caseosa
A
Third trimester
15
Q
Initial unstructured multiplication of cells
A
Morula
16
Q
Morula divides to form a
A
Blastula
17
Q
2 main parts of a blastula
A
Trophoblast
Inner cell mass
18
Q
Trophoblast becomes the
A
Placenta of fetal origin
19
Q
Inner cell mass becomes the
A
Embryo
20
Q
Inner cell mass differentiates into this 3-layered structure
A
Gastrula
21
Q
First stage where skin development separate from the development of other organs
A
Gastrula
22
Q
Ectoderm forms the
A
Epidermis
Melanocytes
Nervous system
23
Q
Mesoderm forms the
A
Fibroblasts
Blood vessels
Muscles
Bone
24
Q
Y/N: Endoderm contributes to skin development
A
No
25
Neural crest development initiates during
Third week
26
Initial stage of neural crest development
When the ectoderm forms the neural plate within it
27
Differentiates into the future central nervous system
Neural plate
28
Part of the ectoderm that remains free in the mesoderm
Neural crest
29
Neural crest migration in the head vs trunk
Head: neural crest migrate before neural tube closure
Trunk: neural crest migration is the last event
30
Persistent neural crests cells that do not complete migration and differentiates into melanocytes are hypothesized to contribute to
Common blue nevi
31
Mesoderm condenses into regular-spaced cuboidal segments which are lateral to the neural tube
Somites
32
Somite formation during
Third week
33
Somites contribute to
Axial skeleton and muscles
| Dermal fibroblasts
34
First step in skin formation
Ectoderm converts to a single later known as the germinativum
35
Germinativum expresses the gene
p63
36
p63 gene corrupted in
EEC syndrome (ectrodactyly-ectodermal dysplasia-cleft syndrome)
37
Flattened cells with tight junctions and polarized cytoskeletal adhesions that form above the germinativum
Periderm
38
Periderm forms at
15 days
39
Lack of periderm formation leads to
Human cocoon syndrome
40
Formed between the periderm on the outside and the germinativum layer
Intermediate layer
41
Intermediate layer forms at
60 days
42
Barrier formation initiating at the
Dorsum and head
43
Most common defect in cornification
Ichthyosis vulgaris
44
Ichthyosis vulgaris caused by defects in
Filaggrin protein
45
Surface ectoderm/periderm keratins
K8/K18
46
Intermediate layer keratins
K1/K10
47
Basal layer keratins
K5/K14
48
Fibroblasts derivation:
Ventral body -
Head -
Back skin -
Ventral body - lateral plate mesoderm
Head - neural crest precursors
Back skin - somites
49
Upper dermal fibroblast progenitor become
Dermal papillae
Arrector pili muscle
Papillary fibroblasts
50
Lower dermal fibroblast progenitor become
Adipocytes
| Reticular fibroblasts
51
Differentiates to myofibroblasts during wounding
Reticular fibroblasts
52
Upper vs lower dermal fibroblast progenitor collagen synthesis
Upper: collagen 3 > collagen 1
Lower: collagen 1 > collagen 3
53
Upper vs lower dermal fibroblast progenitor markers
Upper: PDGFRa+, Blimp1+, Dlk-, Irig+
Lower: PDGFRa+, Blimp-, Dlk+
54
Type of adipose thats stores energy as lipid
White adipose
55
Type of adipose thats burns energy through the uncoupling of oxidative phosphorylation to generate heat
Brown adipose
56
Brown adipose cells located in
Paracervical/interscapular
| Supraclavicular areas
57
Transcription factor important for both white and brown adipose development
Peroxisome-proliferator-activated receptor gamma (PPAR gamma)
58
Transcription factor uniquely important food brown adipose development
Prdm16
59
Manifested as herniations appearing a soft yellow to red noodles appearing in Blaschko lines and ulcers at sites of absent skin
Focal dermal hypoplasia or Goltz syndrome
60
Goltz syndrome caused by mutations in the
PORC gene
61
Berardinelli-Seip caused by
Defects in the lipid synthesizing AGPAT2 gene
62
Melanocytes by be detected by the _____ week EGA in human epidermis
8th
63
_____-positive progenitor can differentiate into glial cells in addition to melanocytes
SOX10
64
When differentiating into melanocytes, SOX10-positive progenitors begin to express the critical transcription factor
Micropththalmia-associated transcription factor (MITF)
| DCT and KIT proteins
65
Dermal melanocytes are thought to persist after birth in several locations
Dorsa of the hands and feet
Sacrum/buttocks
Scalp
*clinically important because they are also common sites for blue nevi
69
Defective melanocyte development where disrupted melanocyte migration occurs due to defects in, for example, c-kit growth factor
Piebaldism
70
Sensory neurons develop from the _____ (head) or _____ (elsewhere)
Trigeminal
| Dorsal root ganglia
71
Merkel cells are found as early as _____ weeks EGA
12
72
Merkel cells highest density at
Volar sites
Appendages
Nerves
73
Stages of hair follicle development
Hair placode (75 days)
Hair germ/bud (80 days)
Peg (100 days)
Bulbous peg (13-14 weeks)
74
Earliest morphologic change in hair formation
Hair placode
75
Keratinocytes become thinner, columnar, tightly packed, and is accompanied by accumulation of congregated or condensed fibroblasts beneath the dermis
Hair placode
76
Downward movement of epithelium forming a clear nubbin
Hair germ/bud phase
77
Epithelium begins to wrap around and encompass the associated inductive fibroblast population, which is now called the dermal papillae
Peg stage
78
Sebaceous glands are formed
Bulbous peg stage
79
First wave of hair production
Lanugo hair (130 days)
80
Y/N: Most lanugo hair is shed before birth
Yes
81
Hair follicle stem cell compartment
Bulge
82
Activity of _____ is perhaps the most important for appendage development
Beta-catenin
83
Sebaceous glands more active during _____ and ______
Embryogenesis (production of vernix caseosa)
| Puberty
84
Sebaceous glands not associated with hair follicles
Orphan sebaceous glands
85
Orphan sebaceous glands locations
Meibomian gland of the eye
Fordyce spots of the mouth
Tyson glands of the prepuce
Montgomery glands of the female areola
86
Sweat glands in the volar skin develop around _____ weeks EGA, and the rest of the body at _____ weeks
12-13
| 20
87
Volar dermatoglyphics development begins around
Week 7
88
Required for the recruitment of angiogenesis-associated cells such as pericytes
Angiopoietin-1
89
_____ released by arteries as a ligand for _____on veins is important to maintain the AV plexus
EphrinB2
| EphB4 receptor
90
Lymphatic development occurs through the maturation of established venous endothelial cells that express
PROX1
91
Sturge-Weber caused by defects in
GNAQ gene
92
Hematopoietic cell development occurs in the following organs (in chronological order)
Yolk sac
Dorsal aorta
Liver
Bone marrow
93
Langerhans cells are detectable by
10 weeks EGA
94
Impaired TH17 development and excessive TH2 profile odds eosinophilia and hyper-IgE characterized by chronic eczema and recurrent skin Staphylococcus aureus infections
Hyper-IgE syndrome or Job syndrome
95
Hyper-IgE syndrome or Job syndrome mutation
Signal transducer and activator is transcription 3 (STAT3)
