(9) Consider the data presented below. If one divides the Xenopus blastula stage
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Question
(9) Consider the data presented below. If one divides the Xenopus blastula stage embryo into 4 sections (animal cap, two sides of equatorial cells, and vegetal cells), and grows each set of cells in a culture dish independently, the cells differentiate into the cell types indicated. When animal cap cells are separated and combined with vegetal cells but not including the equatorial cells the outcome is that animal cap cells in contact with vegetal cells become mesoderm; other animal cap cells become ectoderm. Vegetal pole cells become endoderm.
Are the equatorial cells committed? The animal cells? The vegetal cells?
Explanation / Answer
If an embryonic cell is autonomously capable of controlling the fate of cells being differentiated by it (including when placed in an external environment like test tube or any other region in the same embryo), then the cells are considered to be committed. Generally, the cells near to equatorial region give rise to mesoderm, the cells near by animal pole gives ectoderm.
In this case, it is given that animal cap cells in contact with vegetal cells become mesoderm and other animal cap cells become ectoderm, and vegetal pole cells become endoderm. This suggests that both animal pole and vegetal pole cells are not committed.
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