4 - Developmental Biology Flashcards

1
Q

Central cells of the epidermis

A

Keratinocytes

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2
Q

Provides structural resiliency

A

Intermediate filament keratins

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3
Q

Central cells of the dermis

A

Fibroblasts

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4
Q

Extracellular secreted proteins; activate the frizzled receptors to eventually stabilize B-catenin

A

Wnt ligands

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5
Q

Transcription factor; central regulator of epithelial identity

A

p63

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6
Q

Extracellular secreted proteins; bind the smoothened receptor and eventually the Gli family of transcription factors

A

Shh ligands

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7
Q

Bind the receptor Notch which initiates transcription and epidermal differentiation

A

Ligands Delta or Jagged

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8
Q

Important in large-scale body patterning

A

HOX (homeobox) transcription factor family

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9
Q

Protein most abundant in the epidermis

A

Keratin

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10
Q

Most abundant protein in the dermis

A

Collagens

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11
Q

When organogenesis has mostly completed

A

First trimester

Weeks 0-12

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12
Q

Appearance of downy hair

A

Second trimester

Weeks 12-26

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13
Q

When most development completes

A

Third trimester

Weeks 26-40

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14
Q

Formation of the vernix caseosa

A

Third trimester

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15
Q

Initial unstructured multiplication of cells

A

Morula

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16
Q

Morula divides to form a

A

Blastula

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17
Q

2 main parts of a blastula

A

Trophoblast

Inner cell mass

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18
Q

Trophoblast becomes the

A

Placenta of fetal origin

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19
Q

Inner cell mass becomes the

A

Embryo

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20
Q

Inner cell mass differentiates into this 3-layered structure

A

Gastrula

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21
Q

First stage where skin development separate from the development of other organs

A

Gastrula

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22
Q

Ectoderm forms the

A

Epidermis
Melanocytes
Nervous system

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23
Q

Mesoderm forms the

A

Fibroblasts
Blood vessels
Muscles
Bone

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24
Q

Y/N: Endoderm contributes to skin development

A

No

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25
Q

Neural crest development initiates during

A

Third week

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26
Q

Initial stage of neural crest development

A

When the ectoderm forms the neural plate within it

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27
Q

Differentiates into the future central nervous system

A

Neural plate

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28
Q

Part of the ectoderm that remains free in the mesoderm

A

Neural crest

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29
Q

Neural crest migration in the head vs trunk

A

Head: neural crest migrate before neural tube closure
Trunk: neural crest migration is the last event

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30
Q

Persistent neural crests cells that do not complete migration and differentiates into melanocytes are hypothesized to contribute to

A

Common blue nevi

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31
Q

Mesoderm condenses into regular-spaced cuboidal segments which are lateral to the neural tube

A

Somites

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32
Q

Somite formation during

A

Third week

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33
Q

Somites contribute to

A

Axial skeleton and muscles

Dermal fibroblasts

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34
Q

First step in skin formation

A

Ectoderm converts to a single later known as the germinativum

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35
Q

Germinativum expresses the gene

A

p63

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36
Q

p63 gene corrupted in

A

EEC syndrome (ectrodactyly-ectodermal dysplasia-cleft syndrome)

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37
Q

Flattened cells with tight junctions and polarized cytoskeletal adhesions that form above the germinativum

A

Periderm

38
Q

Periderm forms at

A

15 days

39
Q

Lack of periderm formation leads to

A

Human cocoon syndrome

40
Q

Formed between the periderm on the outside and the germinativum layer

A

Intermediate layer

41
Q

Intermediate layer forms at

A

60 days

42
Q

Barrier formation initiating at the

A

Dorsum and head

43
Q

Most common defect in cornification

A

Ichthyosis vulgaris

44
Q

Ichthyosis vulgaris caused by defects in

A

Filaggrin protein

45
Q

Surface ectoderm/periderm keratins

A

K8/K18

46
Q

Intermediate layer keratins

A

K1/K10

47
Q

Basal layer keratins

A

K5/K14

48
Q

Fibroblasts derivation:
Ventral body -
Head -
Back skin -

A

Ventral body - lateral plate mesoderm
Head - neural crest precursors
Back skin - somites

49
Q

Upper dermal fibroblast progenitor become

A

Dermal papillae
Arrector pili muscle
Papillary fibroblasts

50
Q

Lower dermal fibroblast progenitor become

A

Adipocytes

Reticular fibroblasts

51
Q

Differentiates to myofibroblasts during wounding

A

Reticular fibroblasts

52
Q

Upper vs lower dermal fibroblast progenitor collagen synthesis

A

Upper: collagen 3 > collagen 1
Lower: collagen 1 > collagen 3

53
Q

Upper vs lower dermal fibroblast progenitor markers

A

Upper: PDGFRa+, Blimp1+, Dlk-, Irig+
Lower: PDGFRa+, Blimp-, Dlk+

54
Q

Type of adipose thats stores energy as lipid

A

White adipose

55
Q

Type of adipose thats burns energy through the uncoupling of oxidative phosphorylation to generate heat

A

Brown adipose

56
Q

Brown adipose cells located in

A

Paracervical/interscapular

Supraclavicular areas

57
Q

Transcription factor important for both white and brown adipose development

A

Peroxisome-proliferator-activated receptor gamma (PPAR gamma)

58
Q

Transcription factor uniquely important food brown adipose development

A

Prdm16

59
Q

Manifested as herniations appearing a soft yellow to red noodles appearing in Blaschko lines and ulcers at sites of absent skin

A

Focal dermal hypoplasia or Goltz syndrome

60
Q

Goltz syndrome caused by mutations in the

A

PORC gene

61
Q

Berardinelli-Seip caused by

A

Defects in the lipid synthesizing AGPAT2 gene

62
Q

Melanocytes by be detected by the _____ week EGA in human epidermis

A

8th

63
Q

_____-positive progenitor can differentiate into glial cells in addition to melanocytes

A

SOX10

64
Q

When differentiating into melanocytes, SOX10-positive progenitors begin to express the critical transcription factor

A

Micropththalmia-associated transcription factor (MITF)

DCT and KIT proteins

65
Q

Dermal melanocytes are thought to persist after birth in several locations

A

Dorsa of the hands and feet
Sacrum/buttocks
Scalp

*clinically important because they are also common sites for blue nevi

69
Q

Defective melanocyte development where disrupted melanocyte migration occurs due to defects in, for example, c-kit growth factor

A

Piebaldism

70
Q

Sensory neurons develop from the _____ (head) or _____ (elsewhere)

A

Trigeminal

Dorsal root ganglia

71
Q

Merkel cells are found as early as _____ weeks EGA

A

12

72
Q

Merkel cells highest density at

A

Volar sites
Appendages
Nerves

73
Q

Stages of hair follicle development

A

Hair placode (75 days)
Hair germ/bud (80 days)
Peg (100 days)
Bulbous peg (13-14 weeks)

74
Q

Earliest morphologic change in hair formation

A

Hair placode

75
Q

Keratinocytes become thinner, columnar, tightly packed, and is accompanied by accumulation of congregated or condensed fibroblasts beneath the dermis

A

Hair placode

76
Q

Downward movement of epithelium forming a clear nubbin

A

Hair germ/bud phase

77
Q

Epithelium begins to wrap around and encompass the associated inductive fibroblast population, which is now called the dermal papillae

A

Peg stage

78
Q

Sebaceous glands are formed

A

Bulbous peg stage

79
Q

First wave of hair production

A

Lanugo hair (130 days)

80
Q

Y/N: Most lanugo hair is shed before birth

A

Yes

81
Q

Hair follicle stem cell compartment

A

Bulge

82
Q

Activity of _____ is perhaps the most important for appendage development

A

Beta-catenin

83
Q

Sebaceous glands more active during _____ and ______

A

Embryogenesis (production of vernix caseosa)

Puberty

84
Q

Sebaceous glands not associated with hair follicles

A

Orphan sebaceous glands

85
Q

Orphan sebaceous glands locations

A

Meibomian gland of the eye
Fordyce spots of the mouth
Tyson glands of the prepuce
Montgomery glands of the female areola

86
Q

Sweat glands in the volar skin develop around _____ weeks EGA, and the rest of the body at _____ weeks

A

12-13

20

87
Q

Volar dermatoglyphics development begins around

A

Week 7

88
Q

Required for the recruitment of angiogenesis-associated cells such as pericytes

A

Angiopoietin-1

89
Q

_____ released by arteries as a ligand for _____on veins is important to maintain the AV plexus

A

EphrinB2

EphB4 receptor

90
Q

Lymphatic development occurs through the maturation of established venous endothelial cells that express

A

PROX1

91
Q

Sturge-Weber caused by defects in

A

GNAQ gene

92
Q

Hematopoietic cell development occurs in the following organs (in chronological order)

A

Yolk sac
Dorsal aorta
Liver
Bone marrow

93
Q

Langerhans cells are detectable by

A

10 weeks EGA

94
Q

Impaired TH17 development and excessive TH2 profile odds eosinophilia and hyper-IgE characterized by chronic eczema and recurrent skin Staphylococcus aureus infections

A

Hyper-IgE syndrome or Job syndrome

95
Q

Hyper-IgE syndrome or Job syndrome mutation

A

Signal transducer and activator is transcription 3 (STAT3)