Differentiation

[ydoaPs]

What are the currrent theories on what causes differentiation?

[fuhrerkeebs]

Evolution occuring in different enviroments, natural selection in general, genetic mutation billions of years ago which--over time--magnified, and the list goes on and on.

[ydoaPs]

huh? that has nothing to do with differentiation.

[fuhrerkeebs]

Genetic differentiation deals with the genetic "differences" in a population. Everything I listed deals with genetic differentiation. If you are not referring to genetic differentiation, then let me know.

[ydoaPs]

differentiation as in a zygote. stem cells turning into other types of cells. ring any bells?

[fuhrerkeebs]

Ah, you mean cellular differentiation. The mechanism that causes it is still unknown, but it is popular belief that it is caused by selective control.

[Sayonara]

I'm pretty sure one of my lecturers at uni went to great lengths explaining this but I am quite pissed right now so he can just shut up.

[ydoaPs]

I'm pretty sure one of my lecturers at uni went to great lengths explaining this but I am quite pissed right now so he can just shut up.

 

what the hell was that about?

[Sayonara]

For you crazy Americans, over here "pissed" = mildly drunk and "pissed off" = what you call pissed.

 

I hope that explains everything.

[ydoaPs]

who is the "he"? that was my question.

[Sayonara]

The lecturer.

[Skye]

What are the currrent theories on what causes differentiation?

Chemical signals sent by surrounding cells that switch on or off certain genes.

[ydoaPs]

how does the origional mass of stem cells decide what will be which type of cell?

[Skye]

The egg cell itself is polarised, one end has a higher concentration of things called fate determinants, which ... determine the fate of the different ends. Fairly often the initial cell division isn't equal as well, so one cell is bigger than the other. Everything is then based around that, and as the embryo grows further axes are defined (depending on the type of symmetry the critter has), then regions within these, and so on in increasing complexity. This isn't a statically growing ball of course, what with blastulation and gastrulation and further large cell movements, so controlling the cell movements is also important.

[Frostrunner]

You just asked a question that took an entire semester for me to learn (in too many different animal models). The short of it is like skye said. The egg is polarized by where the sperm enter and from there on out think of it as friends (cells) telling their nieghbors what to do and how to do it through the mechanism of cellular signaling and gene pathways that will make anyone tired of memorizing.

[ans]

In simple terms is it correct to say that what determines what stem cells differentiate into is their environment (eg chemicals around the cell)