4 - Developmental Biology Flashcards
Central cells of the epidermis
Keratinocytes
Provides structural resiliency
Intermediate filament keratins
Central cells of the dermis
Fibroblasts
Extracellular secreted proteins; activate the frizzled receptors to eventually stabilize B-catenin
Wnt ligands
Transcription factor; central regulator of epithelial identity
p63
Extracellular secreted proteins; bind the smoothened receptor and eventually the Gli family of transcription factors
Shh ligands
Bind the receptor Notch which initiates transcription and epidermal differentiation
Ligands Delta or Jagged
Important in large-scale body patterning
HOX (homeobox) transcription factor family
Protein most abundant in the epidermis
Keratin
Most abundant protein in the dermis
Collagens
When organogenesis has mostly completed
First trimester
Weeks 0-12
Appearance of downy hair
Second trimester
Weeks 12-26
When most development completes
Third trimester
Weeks 26-40
Formation of the vernix caseosa
Third trimester
Initial unstructured multiplication of cells
Morula
Morula divides to form a
Blastula
2 main parts of a blastula
Trophoblast
Inner cell mass
Trophoblast becomes the
Placenta of fetal origin
Inner cell mass becomes the
Embryo
Inner cell mass differentiates into this 3-layered structure
Gastrula
First stage where skin development separate from the development of other organs
Gastrula
Ectoderm forms the
Epidermis
Melanocytes
Nervous system
Mesoderm forms the
Fibroblasts
Blood vessels
Muscles
Bone
Y/N: Endoderm contributes to skin development
No
Neural crest development initiates during
Third week
Initial stage of neural crest development
When the ectoderm forms the neural plate within it
Differentiates into the future central nervous system
Neural plate
Part of the ectoderm that remains free in the mesoderm
Neural crest
Neural crest migration in the head vs trunk
Head: neural crest migrate before neural tube closure
Trunk: neural crest migration is the last event
Persistent neural crests cells that do not complete migration and differentiates into melanocytes are hypothesized to contribute to
Common blue nevi
Mesoderm condenses into regular-spaced cuboidal segments which are lateral to the neural tube
Somites
Somite formation during
Third week
Somites contribute to
Axial skeleton and muscles
Dermal fibroblasts
First step in skin formation
Ectoderm converts to a single later known as the germinativum
Germinativum expresses the gene
p63
p63 gene corrupted in
EEC syndrome (ectrodactyly-ectodermal dysplasia-cleft syndrome)