Thread: In the human body, what cells are non-dividing?

I want a list of all the kinds of non-dividing cells in the human body.
1. Neurons (all neurons?)
2. Spermies
3. Etc...

dead cells usually stop dividing.

Why do you want a list? Any terminally differentiated cell is no longer dividing. That list would be pretty huge.

unless they de-differentiate.

Originally Posted by spuriousmonkey

unless they de-differentiate.

Blasphemy!

It happens though.

Originally Posted by spuriousmonkey

It happens though.

I know, but it's still blasphemy.

I just want a list of the types of cells that normally don't divide. Red blood cells don't divide do they? Cells in the kidney or most other organs do divide regularly right? Or is that wrong?

Originally Posted by Baconator

I just want a list of the types of cells that normally don't divide. Red blood cells don't divide do they? Cells in the kidney or most other organs do divide regularly right? Or is that wrong?

Roughly right, yes.

Typically, tissue cells in organs are arranged in layers with a layer of dividing cells pushing new cells constantly outwards. The classic example being skin cells. At the deepest level, cells are diving. However the cells that are generated by this layer do not divide. They are pushed outwards by new cells coming from the dividing layer and eventually die at the outermost layer, to be replaced by the cells below them. Similar arrangements are seen in the lungs and other mucosal surfaces, as well as in various organs. Where the layered system is not observed, we still generally see a set subpopulation of cells diving to generate new non-dividing cells. So new tissue tends to be generated in defined areas. The dividing cells, whether in layered or unlayered tissue, or generating circulatory cells, are broadly called stem cells.

Red blood cells represent a "terminally differentiated" group of cells. They are generated by dividing stem cells in the bone marrow, mostly in the larger limb bones such as the femur. So RBCs don't divide, but other cells in the circulation such as T cells and B cells will divide if they are involved in an immune response.

As a general rule then:

The bulk of cells in most organs do not divide. They tend to be generated by a smaller population of tissue-specific stem cells. Most types of red and white blood cells also do not divide, but are generated by dividing cells in the marrow and lymphatic system.

Excuse my feeble mind but wouldn't the list become even longer due to certain stem cells that simply "become" other cells?

Originally Posted by DecemX

Excuse my feeble mind but wouldn't the list become even longer due to certain stem cells that simply "become" other cells?

I was referring to tissue-specific stem cells, which are themselves derived from more widely potent stem cells. These are derived from yet more stem cells with again a wider potency. Usually (depending on tissue) there's several layers in that hierarchy, eventually going back to embryonic stem cells which are pluripotent, ie capable of eventually becoming all cell types. At each level in the heirarchy, the cells are fewer and fewer.

In terms of the bulk of cells in a body, dividing cells are in the minority.

Although this is a very enlightening discussion. Baconator, I don't see this happening.

Thanks TheBiologista for the good info. I realize my question was a bit flawed.

Anyways, I would like to know what cells we are born with that never really get replaced (like eggs in women). Are there any other cells (like neurons)? Or is my question kinda confusing again?

The answer isn't that simple. depends who you ask. And when.

When we are born pretty much all cells are dividing, this is essential for growth to happen. (that is an oversimplification btw)

As far as cells dividing in the normal adult, generally cells can be divided into 3 catagories.

(i) Labile cells which are constantly dividing and are derived from stem cells such as the GI epithelium or mucosal linings as these are constantly subject to damage/sloughing
(ii) stable cells which do not replicate or do so at a very low level normally but if injured can be stimulated to divide, this would include hepatocytes or the renal tubular cells as someone asked earlier.
(iii)permanent cells, do not and cannot divide/regenerate if damaged, this would include your neurons and others e.g. cardiac myocytes.

I should point out that just because cells dont divide doesnt mean there is not some compensation/healing process. your cardiac myocytes would be replaced by fibrinous tissue in the case of a heart attack. Or skeletal muscle since it tends not to divide, increases in size (hypertrophies) without the nuceli dividing

It's actually much worse than that. When you are born there is mostly a culling going on in the brain. It's not even about dividing or not dividing. It's about being actively eliminated or not.

Genocide on scale not seen before in human history. And it is going on in every baby.

Originally Posted by Baconator

Thanks TheBiologista for the good info. I realize my question was a bit flawed.

Anyways, I would like to know what cells we are born with that never really get replaced (like eggs in women). Are there any other cells (like neurons)? Or is my question kinda confusing again?

Not neurons anyway. Our brains grow and develop pretty much throughout life. Most growth occurring during infancy and childhood, with some fairly significant restructuring during adolescence. There's some evidence in mouse models to suggest that memory formation is dependant on new neuron growth. And of course, we lose neuron cells progressively in old age.

Our brain mostly cuts down during infancy.

this is the dumbest poll and should be closed

obviously the creator didnt know what he/she was talking about