1. It is possible to excise small pieces of early frog embryos, insert these pie

Question

1. It is possible to excise small pieces of early frog embryos, insert these pieces into older embryos, and follow the course of the development of the transplanted material as the host embryo continues to develop into a tadpole. In the figure below, tissue that would later develop into an eye is removed either from the late blastula stage (a) or the much later neurula stage (b). The tissue is then transplanted into a much older host embryo, cither being placed into the anterior head, the lateral head, or the central dorsum. When the donor tissue comes from a younger stage, it develops in the host into whatever tissue is appropriate for the new location, i.e. brain tissue, an ear, or a portion of the kidney. In contrast, tissue from the neurula-stage donor continues to develop into an ectopic eye regardless of its placement within the host. Explain these results. (50 points) a) Tissue from late blastula b) Tissue from neurula or early gastrula Area that will later beoame neura tissue Excise tissue Excise tisSue become an eye Transplant into oider host embryo Transplant into oider host embryo Develcps into a kidney into an eye Develops into Develops head material into an ear eye, brain) Develops Develops nto an eye into an eye

Explanation / Answer

This happens because the tissue from the last blastula stage was In its potent state which means it was not committed to its development. That's why, when it was transplanted into older host embryo whose tissue were committed and determined, it gets committed to become that tissue like kidney, head material or ear whereever it was placed.

But on the other hand, as the tissue from the later neurula stage was already committed to become an eye of the tadpole therefore, when it was placed in all the three parts of the older host embryo it developed into an eye only.

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