Question

The neural plate forms as a flat plate that eventually forms a tube with the lateral edges meeting dorsally to form the neural crest. Neural plate cells grafted from the presumptive spinal chord area in the presumptive eye area turn into eye cells if the graft is done while the plate is open; but if the graft is done as the plate closes to form the neural tube, the graft turns into spinal chord tissue in the eye. Your hypothesis is
a. cell fate in the neural plate is not determined while the plate is open
b. cell fate in the neural plate is not permanently fixed while the plate is open
c. cell fate is determined while the plate is open
d. all of the above
e. none of the above

Answer 1

Answer:

A

Explanation:

Cells have a cellular "memory" that tells them in what sense, when and where they should differentiate, and then maintain that state. The decision to differentiate occurs before the same differentiation. Thus, from the somites cells migrate to the extremities and there differentiate into muscle cells, while the cells that were already there differentiate in another sense, for example, connective tissue. The cell that makes that decision is determined. Determination involves a change that has the following characteristics:

A concrete path of development.

Internal. It does not depend on the environment in which it is found because of its position in the embryo.

Self-perpetuating. The cell already determined does not lose its memory nor its character defined in a concrete way when the circumstances that produced it vary. This is equivalent to saying that the change is almost irreversible.

Inherited. It is transmitted to your daughter cells (cellular memory).

Cell fate is what a cell (or group of embryonic cells) normally becomes. For example, the cells of vertebrate myotomes become muscle cells, and those of the dorsal lip of the blastopore of an amphibian become notochord cells. Specification refers to what is produced by an embryonic cell isolated in a neutral medium, which may be different from its normal fate. Thus, the cells of the animal pole (animal capsule) of the amphibian blastula Xenopus laevis can produce epidermis and neural tube (their cellular destinations), while isolated in neutral medium only generate epidermal cells. Therefore, the cells of the animal capsule of the Xenopus blastula are specified to produce epidermis. This concept is independent of the processes of determination and differentiation.

Source: Biology. Curtis 8th edition.

Biología celular y molecular, 4e Ricardo Paniagua, Manuel Nistal, Pilar Sesma, Manuel Álvarez-Uría, Benito Fraile, Ramón Anadón, Francisco José Saéz