Explain gastrulation and summarize the germ layers produced during this process
What will be an ideal response?
Gastrulation is the rearrangement and migration of the cells of the bilaminar embryonic disc to form the trilaminar embryonic disc. This is the stage at which the three germ layers develop. The first cells that migrate in this way become the inner germ layer, or endoderm, which replaces the hypoblast. The next cells that migrate to a position between the epiblast and endoderm, and this becomes the middle layer, the mesoderm. The remaining cells of the epiblast form the outer layer, the ectoderm.
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Platelets are
A) large cells that lack a nucleus. B) large cells with a prominent, indented nucleus. C) small cells with a many-shaped nucleus. D) fragments of large cells. E) small cells that lack a nucleus.
Helper T (TH) cells recognize antigens when they are bound to a(n) ________
A) hapten B) natural killer cell C) major histocompatibility complex (MHC) protein D) immunoglobulin E) basophil
Papillary muscles prevent the AV valves from prolapsing (bulging) excessively into the atria when the ventricles contract
Indicate whether the statement is true or false
A man suffers a shoulder injury, and as a result has very little strength when he tries to flex his forearm. The nerve most likely damaged is the
A) axillary nerve B) median nerve C) musculocutaneous nerve D) radial nerve E) ulnar nerve