L01/2
What is the goal of gastrulation?
Form 3 germ layers from the epiblast to become trilaminar (which gives rise to all tissues and organs)
What layer forms the primitive streak
epiblast layer
What is the accumulation of mesenchymal cells along the median plane (mesodermal)
notochordal process
Describe neurulation
spontaneous abortion/ misscarriage
Which gene: involved in symmetry, anterior-posterior (saggital) axis patterning, and CNS development
Shh
What is at the cranial end of the primitive streak
primitive node
The ___ is mesodermal and extends cranially from the primitive pit to the prechordal plate.
notochord *and it starts out as the notochordal process
What 3 sources is the PNS derived from
neural crest cells (ectoderm), neural tube (ectoderm), mesoderm
If the primitive streak fails to regress, what clinical correlate is involved? Is this an error occurring in gastrulation or neurulation?
teratoma- gastrulation
Which gene: part of TGF-B family, up regulates genes for dorsal and ventral mesoderm formation, and INDUCES PRIMITIVE STREAK
NODAL BABY
What signals the beginning of gastrulation?
primitive streak
Which gene is important for the dorso-ventral axis formation?
Wnt signaling (Wnt-7 gene)
Which germ layer gives rise to dura mater
mesoderm
Which neural tube defect of neurulation happens when there is a failure to close the anterior neuropore?
anencephaly
Tell me what BMP4 does
signaling factor, mesoderm formation, ectoderm differentiation (CNS)
Cells that move through the primitive streak will replace the hypoblast to form the endoderm. After that mesoderm formation starts. What happens to cells that remain in the epiblast?
Become definitive ectoderm, including neural plate
Which gene is important for anterior-posterior axis patterning?
Shh
What are the roles of noggin and chordin?
Antagonize BMP
Which neurulation defect occurs as a failure to closing the posterior neuropore?
spinal bifida
Which neurotransmitter plays a role in left-right axis determination?
What is ingression?
Movement of epiblastic cells down the primitive streak and through the primitive groove
Which body axis is initiated before gastrulation?
dorso-ventral
When BMP is blocked, it specifies the tissue to neural ectoderm. When BMP is not blocked in certain areas that remain, what is formed?
Skin
What chemical is elevated in patients with a neural tube defect?
alpha fetoprotein