A totipotent cell is a cell that has the ability to develop into any cell type in the organism, including all the extraembryonic tissues (like the placenta in mammals).
Here's a more detailed explanation:
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Definition: Totipotency is the capacity of a single cell to divide and differentiate into all the differentiated cells in an organism. This includes all three germ layers (ectoderm, mesoderm, and endoderm) and the placental tissues.
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Examples:
- Zygote: The fertilized egg is the prime example of a totipotent cell in animals. It can give rise to a complete organism.
- Blastomeres (early cleavage): In the early stages of embryonic development (cleavage), the cells produced (blastomeres) are also considered totipotent up to a certain point.
- Plant cells: In plants, cells from the meristematic tissues are considered totipotent. They can differentiate into any cell type within the plant and even regenerate a whole new plant.
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Loss of Totipotency: As development progresses, cells become more specialized and lose their totipotency. They become pluripotent (can differentiate into many, but not all, cell types) and then multipotent (can differentiate into a limited range of cell types).
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Significance: Understanding totipotency is crucial in developmental biology and has implications for regenerative medicine and cloning technologies. For instance, induced pluripotent stem cells (iPSCs) are created by reprogramming differentiated cells to regain pluripotency (not totipotency) and can then be directed to differentiate into specific cell types for therapeutic purposes.
