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#Question id: 7178


In sea urchin, the large micromeres are autonomously specified. They inherit maternal determinants that were deposited at the vegetal hemisphere of the egg; these become incorporated into the large micromeres at fourth cleavage. When an isolated animal hemisphere is combined with isolated micromeres, then what will be the result?

#Unit 5. Developmental Biology
  1. A recognizable pluteus larva is formed, with all the endoderm derived from the animal hemisphere.
  2. Animal hemisphere becomes a ciliated ball of undifferentiated ectodermal cells.
  3. Micromeres differentiate into skeletal rods while the induced animal cap cells to form ectoderm.
  4. The vegetal cell fates are not specified, and the entire embryo develops as a ciliated ectodermal ball.