MCB 141 Quiz 3
Name:
1) Name one tissue type which is present and one tissue which is absent in a
ventralized embryo (one lacking an organizer). Be sure to indicate which is
which. (2pts)
Present: ciliated epidermis, coelomic mesoderm, blood, and hindgut
Absent: notochord, gill slits, dorsal hollow nerve cord, tail, heart, anterior gut
3) Label the early gastrula diagram to indicate which parts of the early
gastrula give rise to each of the labeled tissues on the tadpole diagram. (3pts)
4) You have discovered a new species of amphibian and want to know if it
develops in the same way as Xenopus. How would you test the following
(6pts):
a) the fate of cells within the grey crescent?
Inject a lineage tracer (for example nile blue) into cells of the grey crescent, allow
the embryo to develop and see what is stained in the tadpole.
b) what the cells of at the vegetal pole are specified to become at the early
gastrula stage?
Remove cells from the vegetal pole and allow them to grow in isolation (in a dish).
See what type of cell they differentiate into.
c) whether the cells at the animal pole are competent to adopt the fate of the
vegetal pole cells at the early gastrula stage?
Remove animal pole cells, label them, and graft them onto the vegetal pole of
another embryo. See whether the labeled cells adopt the same fate as the
endogenous vegetal pole cells.
5) What happens to the number of pole cells when Oskar dosage is increased?
The number of pole cells increases.