Regenerative medicine science: the regeneration of plants can develop into individuals, so why can't animals?

Hello home, let's continue to explore stem cells together. The last lesson was about regenerative medicine, the definition of regenerative medicine, the totality of regenerative medicine cells, and a question left at the end. It is that the regeneration of our plants can develop into individuals. So why can't we animals?

Today we'll talk about animal regeneration. Although animals can not just take out some part of the plant like a plant culture will soon form a new plant, but it also has a certain regeneration ability, and the lower the animal regeneration ability is stronger. For example, earthworms, you cut into several sections, it can still grow, and you cut into several sections, it can grow into several individuals. There are also examples of geckos broken tail, can grow a new tail, tadpoles can regenerate a new tail out in a few hours. And there is no scar. But the higher the animal the weaker this ability. The most typical example is the process of turning a tadpole into a frog. When it is still a tadpole, the lost tail can still grow back. But when it grows into a frog, it loses this regenerative ability.

So where does the animal's ability to regenerate come from? We all know that all multicellular animals start from a cell development, the way of development, is the cell division: one becomes two, two becomes four, is a geometric expansion. In this process of expansion, the initial cell is divided equally, and the cell's reasonable nuclear material is replicated in two sets, which are packed in two daughter cells. The cytoplasm also has to divide equally into the two daughter cells, and after a few generations of division, the cell begins to divide unequally. The nuclear material is still the same, replicated and distributed, but the cytoplasmic material then begins to be biased, with some material divided into this cell to make this cell grow in one direction and certain material divided into that cell to make that cell grow in the other direction. This is when the cells start to go their separate ways, with most of them going further and further away and eventually differentiating into terminal cells, that is, cells that can never become other kinds of cells again.

But there are some cells that stop midway and maintain a property of differentiating forward all the time. These cells have the ability to differentiate into multiple potential cells, but lose the ability to develop into a complete individual, and their developmental potential is somewhat limited. The differentiation potential of multipotent hepatocytes is called pluripotency.

Normally these pluripotent stem cells just stay in their own world and wait for the need to give a command, they get active and start dividing. In the case of unequal division, they are able to differentiate into the kinds of cells that the organism needs in a healed order, and then flood the area where they are needed. This is the piece of differentiation and regeneration of our animal cells

So where does their pluripotency come from? This starts with developmental genetics. Embryonic development of organisms is a process of gene regulation, where different genes are turned on and off in sequence, often by the continuous expression of older ancestral genes. Therefore, the process of embryonic development is a process of sequential expression from ancestral genes to advanced genes. In other words, a process of gradual gene expression.

Therefore, in the evolutionary process, the older the animal, the simpler it is, and the more advanced the animal, the more complex it is, and the earlier the genes expressed have a greater impact on the organism. After these genes are sequentially turned on for expression, the cell is on the path of no return and can never go back. That is, the simpler the organism, the easier it is to start from scratch. The more complex an organism is, the less likely it is to start from scratch.