How does the cells in bilaterally symmetric organisms know to grow in mirror images of each other

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By my current understanding of biology, the genes tell each cell to do different things (differentiate, split etc) depending on the local neighbourhood of the cell (is this even right?).

How do they know to grow in symmetric pairs then if their corresponding mirror image cell is nowhere near their local neighbourhood?

In: Biology

2 Answers

Anonymous 0 Comments

Early on in development we are essentially a sphere of cells, then a ridge forms along the sphere, and the sphere divides from there. During these early phases, cells begin down the pathway to specificity. So it’s not like the cells on one side decide to form into a kidney, and mirror the other kidney cells on the other side. But more that in the very early stages, two separate clumps of cells decide that they are each going to become kidneys, and then those cells move further and further apart as we grow and continue their independent growth to each become a full kidney.

This is a fairly complex topic of biology, but googling “embryologic organogenesis” should give you a lot of good results and videos that explain the process in more detail.

Anonymous 0 Comments

At the most basic level, you are correct genes contain a cell’s blueprints to tell it what to do. However, different genes are activated in different cells which is how we get different organs with different functions.

Which genes are activated and where/when they are activated is a complex process that involves cell signaling. There are four types of cell signaling.

1. A cell can signal itself/similar cells based on environmental factors. (autocrine)
2. A cell can signal another cell that it is directly next to via physical connections between the cell. (direct contact)
3. A cell can release signaling molecules that will only affect cells in its local area even if they aren’t physically touching. (paracrine)
4. A cell can release signaling molecules in the bloodstream to affect distant cells. (endocrine)

The important ones that determine development are autocrine, paracrine, and direct contact mechanisms (so the influence is local and not distant between mirrors). I would also say that the corresponding tissue is developing independently of its mirror e.g. You don’t need one kidney to tell the other to develop.