im new here and thought id just offer my two pennies or any other form of interchangable currency.
There are a few things you have to remember about cells
Every cell has a full set of the genetic code of the particular individual... so every cell in your body has the full set of blueprints.
The DNA in the nucleus of everycell can be controlled... every encoding part of the genetic code has activation/dectivation sites, meaning that every
single gene can be switched on, or off... so every gene can be expressed or not.
Cells dont react to their DNA, their genetic code (or at least most cells dont), they react to their local environment, they react to what hormones,
neuroreceptors and whatever other chemicals are in the near vicinity. They have the ability to "perceive" their environment and switch their DNA on
and off... so if theyre in an environment where there is no "chemical X" they wont express the genes designed to deal with "chemical X"
Cells talk to each other ... every cell releases chemical signalls telling the cells around it how to react.
So what you have during embryogenesis is a chicken and egg situation... you have a cell with the full blueprints doing as they dictate untill there
are enough cells to start communicating with each other... then they start to change, one cell suddenly starts being say the skin precursor cell, and
tells the other cells that its doing this, it has the monopoly and the other cells wont do the same thing. It will then make more of itself
surrounding the embryo in an epithelial layer (i know this isnt quite true, but for the sake of an explanation im simplifying a lot).
So what you end up having is a group of cells reacting to the environment they have made for themselves because of the systems found within them that
make them react to the environment
and ive managed to confuse myself
what im saying is DNA doesnt control what the cells do... their environment does, their environment switched the DNA segments on and off... and in
embryogenesis the original environment is created from the DNA...
So fertilied egg cells have to follow a certain preordained path (determined by DNA) untill they "break free" of this template and start reacting to
one another and splitting following different genetic paths ...
In a way you could look at it as sped up evolution except that all the information is already found in the cell.
Wow this is so hard to explain
... ill have to look into a better way of trying to explain this and maybe post it tomorrow
hopefully this isnt too all over the place and people understand what im trying to say.
*Great Topic BTW*