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.

Explanation / Answer

1.a. The Donor Tissue explanted next to the shh host tissue is stage-4- Presumptive Neural plate.

Ventral signal is released to induce this marker.

Intermediate Neural crest cells has been induced.

The vertebrate central nervous system is undergone patterning through a series of inductive methods. To a great deal is known about the ventral signals that pattern the spinal cord. Stage-4 pre-sumptive neural plate is sufficient to dorsalize neural explants in the absence of other embryonic cell types.This induces the formation of new intermediate neural crest cells.

1.b. The other cell types that are expected to be observed are the : Wnt-1 and Wnt-3a.They are observed in adjacent but in the non-overlapping regions of the same graft.Wnt-1 expression can be induced in the ventral regions of the neural tube placed in contact with the Non-neural Ectoderm.

2. The Donor tissue explanted next to the Host neural tube that expresses HB9 is INTERMEDIATE NEURAL PLATE.

Dorsalising signal is released to induce this marker.

Intermediate Neural crest cells and Non- neural Ectoderm are the cell types that has been induced.

when interrmediate neural plate tissue was explanted, and placed in contact with non-neural ectoderm ,Wnt-1, Wnt-3A and few Wnt-mRNA Were observed in high percentage of cultures after 48 hrs.These neural crest cells appeared to have a typical migratory morphology extending numerous Filoapodia and were often observed several cell diameters away from the initial explant.

3. shh signal in part A and HB9 signal in part B generate Neuronal diversity in the ventral spinal column by the creation of Ventral progenitor population and generic of distinct sub-populations within these progenitors.

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