Chapter 5 Lectures 12-13 Flashcards
The principal inductor in primary neural induction is the
A. Hypoblast
B. Primitive streak
C. Extraembryonic mesoderm
D. Notochordal process
E. Embryonic ectoderm
D. Notochordal process
Which of the following tissues arises from cells passing through the primitive streak?
A. Embryonic endoderm
B. Hypoblast
C. Cytotrophoblast
D. Primary yolk sac
E. Amnion
A. Embryonic endoderm
Cells of which germ layer are not present in the oropharyngeal membrane?
A. Ectoderm
B. Mesoderm
C. Endoderm
D. All are present
B. Mesoderm
The pre chordal plate plays an important role in regionalization of the:
A. Notochord
B. Forebrain
C. Embryonic mesoderm
D. Primitive node
E. Hindbrain
B. Forebrain
Brachyury, a deficiency in caudal tissues in the body, is caused by a mutation in what gene?
A. Lim-1
B. Noggin
C. T
D. Sonic Hedgehog
E. Activin
C. T
Which layer of the bilaminar (two layered) embryo gives rise to all of the embryonic tissue proper?
Epiblast
Of what importance is the primitive node in embryonic development?
Acts as the organizer of the embryo. Through it pass the cells that become the notochord. The notochord induces the formation of the nervous system. The primitive node is also the site of synthesis of morphogenetically active molecules, such as retinoic acid. If a primitive node is transplanted to another embryo, it stimulates the formation of another embryonic axis.
The migration of mesodermal cells from the primitive streak is facilitated by the presence of what molecules of the extracellular matrix?
Hyaluronic acid and fibronectin
What molecules can bring about mesodermal induction in an early embryo?
Vg1 and Acvtivin
At what stage in the life history of many cells are cell adhesion molecules lost?
Cell adhesion molecules are lost in a migratory phase. When the migratory cells settle down, they may re-express cell adhesion molecules.
