In newly formed neural tube, the intermediate region close to the sulcus limitan

Question

In newly formed neural tube, the intermediate region close to the sulcus limitans, has been not exposed to molecules that induce ventral or dorsal characteristics. You perform explant experiments in which you take intermediate neural tube (host tissue) and culture them with donor tissue explants that induce specific spinal cord markers in the host explant.

1. The induced host tissue express Shh following transplant.

a. What donor tissue have you explanted next to the host tissue, what signal is released to induce this marker, and what cell type has been induced? Briefly explain your reasoning.

b. What other cell types do you expect to observe? Briefly explain your reasoning.

2. The induced host neural tube expresses HB9. What donor tissue have you explanted next to the host tissue, what signal is released to induce this marker, and what cell type has been induced? Explain your reasoning.

3. How does the signal in parts A and B generate neuronal diversity in the ventral spinal cord? Use only 3 sentences.

4.The host animal is transgenically modified so that Shh irreversibly binds to the receptor. What do you expect to observe with the experiment in Part A?

Explanation / Answer

The original neural tube is composed of germinal neuro epithelium this is the layer of rapidly dividing neural stem cell and others have shown that all cells of the germinal epithelium are continuous from the luminal surface of the neural tube to the outside surface. DNA synthesis(s phase) occur while the nucleus is at the outside edge of the neural tube,is at the nucleus migrates luminally as the cell cycle proceeds . Mitosis occurs on the luminal side of the cell layer if mammalian neural tube cells are labeled with radioactive thymidine during early development these neuronal and glial cells then migrate and differentiate out side the neural tube As the cells adjacent to the lumen continue to divide the migrating cell form a second layer around the original neural tube .this new layer is called the mantle zone.

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