What is a blastocyst?
group of cells with cyst in the middle
Bilaminar Disk
Outer and Inner cell mass, undifferentiated cells or embryonic stem cells
What is an embryonic stem cell?
cells that can become any tissue
What is main difference in adult stem cell?
organ specific differentiation
ex.) liver cell likely to become a liver cell
Ectodermal Stem cells
makes skin or nervous system cells, depending on hormones
Epithelial stem cells
skin cells
Neural stem cells
neuroblasts become neurons
spongioblasts become glia
When is the trilaminar disk created?
two weeks post fertilization
what is the ectoderm?
skin, brain cells and some glands
What is endoderm?
becomes inner tubes of gut and vessels
What is mesoderm?
connective tissue development and form somites
What is the notochord?
architect of embryological development
releasing hormones in embryo at right time (introduction of differentiation)
What is the neural plate?
thickening of neural ectoderm
What does the neural tube become?
the CNS
What does neural crest become?
the PNS (ganglia and nerves), dragged into final location by somites
When does neuropores of the neural tube begin to close?
week 4, anterior before posterior
What are the somites formed from?
mesoderm
What is a somite?
special area in mesoderm which can become vertebrae, muscles, cartilage, tendon and skin
What is the alar plate?
dorsal portion of neural tube in cross section, sensory portion
What is the basal plate?
ventral portion of neural tube, motor portion
What sulcus separates alar and basal plate?
sulcus limitans
What are the 3 primary vesicles of embryo?
pro-, mes- and rhombencephalon
What are the secondary vesicles of embryo?
- Pro- becomes Tel- and Diencephalon
2. rhom- becomes Met- and myelencephalon
What is the cephalic flexure?
between prosencephalon and mesencephalon
responsible for change of axis
What is pontine flexure?
between met and mylen- for cerebellum
happens last
What is cervical flexure?
transition to spinal cord
What does telencephelon become?
lateral ventricles 1-2 and cerebral hemispheres
What does diencephalon become?
third ventricle at its center and thalamus, retina and hypothalamus
What does mesencephalon become?
cerebral aqueduct and midbrain
What does metencephalon become?
fourth ventricle and pons and cerebellum
What does mylencephalon become?
fourth ventricle and central canal and medulla
Time points for primary neural defects?
formation of neural tube- 4 weeks
formation of encephalon- 6 weeks
Spina Bifida
failure of closing of posterior neuropore before sinking into mesoderm
Anencephaly
failure of closing of anterior neuropore before sinking into mesoderm
What are causes of spina bifida?
drugs, nutrition, toxins etc.
What is the sonic hedgehog hormone?
binds with receptors and alters gene expression
promotes normal development of ectoderm, mesoderm and endoderm
What happens with abnormal SHH?
holoprosencephaly- single hemisphere
cerebellar tumors
basal cell carcinoma- skin cancer