how do cells know where to stop being liver/lung/etc and start

>>9125870
Cells don't go from one differentiated cell type (liver or lung) to another, especially if that type is in a completely different tissue group (connective which is skin/bone and other stuff). iPS cells definitely can't do that. Cells start from undifferentiated stem cells and begin specialising based on their position in the body and signals from other cells.

A better question to ask would be what causes stem cells to specialize. This board needs a stupid questions thread if there isn't already one.
>>>/fit/sqt

>>9125996
How do stem cells know their position?

>>9126144
They don't
much like clay doesn't know what the hand that is shaping it wants it to be

>>9126144
Gps

>>9126148
Then whats molding the cells? Gods undying will or grothendeik schemes?

>>9126144
quorum sensing.

>>9126152
DNA, hormones, adjacent cells

>>9126144
Molecules can be secreted and the incident rate of their detection by complementary receptors can indicate distance from the secretor, like a placenta

>>9126153
>eukaryotes
>quorum sensing
Qs is the precursor to cell signalling, if you mean cell signalling say cell signalling

>>9126154
Then what molds the adjacent cells and triggers the hormones?

>>9126162
DNA, hormone secretors

>>9126163
But arent those secretors identical to every stem cell? How does oe go "im gonna trigger liver formation but not lung formation"?

>>9126171
hormones aren't secreted by stem cells

>>9126178
I dont understand. Are hormones just for stopping the differentiation? If so what makes the stem cell start it? And what secretes hormones and what forms that?

>>9125870
Why is the standard for biology and medicine on this board so low yet there are so many CS and maths threads on here?

>>9126181
Generally, morphogens initiate feedback loops during embryonic development. The initial part of the distribution is mostly stochastic; 2-4 cells each have a specific amount of inducer, not more or less than the other cells to trigger the feedback loop. Upon cell division, stochasticity will result in uneven distribution of cellular components and one cell will start oppressing other cells.

Bicoid in Drosophila is a good example; generally, Drosophila has many more interesting genes that have been studied well. Vertebrates have Hox genes that do this.

>>9126144
Undiferentiated cell: It smells too much like placenta in here. That neighboor smells like up. I probably should be skin or something.

Undiferentiated cell: my neighboor is skin, it doesn't smell too much like up, or down. I must be in the middle of everything. Let's become a liver cell!

Undiferentiated cell: It sure smells in there like liver. I know! Let's become a liver cell!

Liver cell: too... Tight... Need... Nutrients...

Another undiferentiated cell: it sure smell like tight in there. I know! Let's become a blood vessel cell!

File: 1501963470544.jpg (59KB, 500x726px) Image search: [Google]

59KB, 500x726px

Y'all be doing biology wrong
>>9125996
>signals
*sign vehicles
>>9126153
>cell signalling
>quorum sensing.
*biosemiotics
>>9126162
>Then what molds the adjacent cells and triggers the hormones?
interpetants
>>9126144
biosemiotics