Occipital hair

[Ventures]

My main concern is why hair from top of the head is so different compared to hair from occipital region (horse-shoe pattern) in a way how it reacts to androgens ? It has same texture, color and structure. Horse shoe pattern is final stage of male pattern baldness. Obviously first clue posters will give in this thread is hair from donor region doesn't have AR or so much of it.

Only hair follicles in top of the scalp are affected negatively by androgens. All other follicles are either stimulated (such as body hair) or not affected (such as eyebrows, eyelashes follicles and occipital hair follicles). And why is that so? Does "androgenic paradox" have to do with theories such as contact inhibition which is related with local tissue effects including inflammation and fibrosis? Of course I know main argument against theories such as galea or contact inhibition theory is fact that hair follicles form donor region transplanted to bald regions of scalp never die.

So, androgens bind with androgen receptors, then the entire androgen/AR complex translocates to the nucleus of the cell where it stimulates certain androgen-dependent genes into beginning the process of RNA transcription/translation. The proteins that are produced as a result of all that are presumably various growth factors and/or growth inhibitors which affect the hair follicle in various ways.

In follicles in top of the head DHT cause dermal papilla to produce growth inhibitors which cause miniaturization of dermal papilla (etc. squeezing). In other parts of scalp as in occipital region which is DHT resistant nothing important happens.

I remember Bryan mentioned every follicle in human body has androgen receptors. But it only matters, how follicles react to DHT. And how do they react is determined by genes inside nucleus of cells.

So, androgens affect:

• body hair follicles in a way to promote / stimulate their growth
• eyebrows, eyelashes follicles in a way which is neutral
• occipital hair follicles in a way which is (relatively) neutral
• hair follicles in other parts of scalp in a way which is supressive

I can't find study which shows that donor hair follicles exposed to extremely high levels of DHT also gradually miniaturize. Which means androgens suppress all scalp hair including hair from back of the head?
We know there are people who have diffuse horse shoe pattern or their pattern over years start gradually to recede to something called NW8.

 

[peacemaker]

I am afraid no one other than a scientist can answer your question, but I think that 2young2retire was getting close to answering the balding pattern question. Paraphrasing his words (I may be wrong), the sides of our head are covered with muscle, whereas the top part, where balding occurs, has only tendons. Maybe when fibrosis happens, it affects the tendon parts much severely than parts covered with muscle as tendons get less blood flow anyway. However, it doesn't quite explain the fact that the hair at the top falls out, whereas the transplanted hair does not. So I believe that our hair at the sides might have something different in them as well.

 

[Ventures]

I guess the reason hair from back and sides of head is resistant lies in fact it contains less androgen receptors (AR) and that area has more blood supply and it's more vascularized compared to galea region which covers top of the scalp. So, combination of both, reduced number of AR and local tissue characteristic (some we know and some we haven't yet fully understood) is the answer why horse-shoe pattern exist in all baldies.

As we know hair located near sides of horse-shoe pattern isn't usually totally resistant and it's known fact during time it falls out. So, local tissue characteristic plays huge role.

What is difference between safe region and donor region ?

 

[DesperateOne]

I have no idea why this is taking so long to cure. I am telling you those re-atomazation machines can't get here soon enough.

 

[Ventures]

Maybe geographical location of donor region (horseshoe pattern) can lead to formation of androgen resistant hair follicles during embryonic and preadolescent development. I got this idea last night. Well, we all know top of the head is less vascularized and there si less blood supply compared to occipital region and sides of the head near ears. So, my incomplete theory is, androgens are crucial for lot of biological mechanisms and development of cell units which require androgen induced chemical signals for proper functioning. Less blood supply turns follicles in those areas to be more androgen sensitive because they need (or they convince themselfs they need) hormones in early stages of human development.

We can test that theory if we transplate hair from the top of the head, of a very young child with male pattern baldness in his family, to back of the head. And then see what happens, when he hit puberty and his 20s or 30s ? Would hair transplanted to back fall out or it would not. And if it wouldn't, that scenario supports my theory that increased androgen sensitivity of hair follicles from top of the head is a result of, I call it "hormone starvation" caused by less blood supply. I am aware, my theory has a lot of holes but I am trying to put together a puzzle.

 

[Helios]

Gotta say that a few months before i found out i had hair loss my eyebrows started to grow out of control. I can 't recall having long eyebrows when i hadn't had any hair loss, but now with hair loss it seems the hair that stopped growing on top of my head is giving my eyebrows an extra boost.

About blood flow, there is more blood flow on top of your head than on the surfaces of your legs, yet the hair there doesn't fall out.

 

[DesperateOne]

Gotta say that a few months before i found out i had hair loss my eyebrows started to grow out of control. I can 't recall having long eyebrows when i hadn't had any hair loss, but now with hair loss it seems the hair that stopped growing on top of my head is giving my eyebrows an extra boost.

About blood flow, there is more blood flow on top of your head than on the surfaces of your legs, yet the hair there doesn't fall out.

Where did you read that you have more blood flow on the scalp than on the legs. I would imagine it might be for a person with no hair loss but on a slick bald guy, the scalp is a wasteland.

Funny you mention the eyebrows, when I was derma rolling hard I noticed an increase in eyebrow thickness. It has come back to normal now that I haven't derma roll in like a month.

 

[Helios]

Where did you read that you have more blood flow on the scalp than on the legs. I would imagine it might be for a person with no hair loss but on a slick bald guy, the scalp is a wasteland.

Funny you mention the eyebrows, when I was derma rolling hard I noticed an increase in eyebrow thickness. It has come back to normal now that I haven't derma roll in like a month.

The brain needs the most heat and your legs need almost no heat, so there is more blood flow around the head than on the legs.
I can tell when i go training in the winter, i can easily go outside with a short when it's freezing.

 

[bushbush]

A lack of blood flow causing hair loss has not been proven.

 

[Ventures]

Are there any cases of people started losing their transplanted hair or noticing thining of hair transplants ?

 

[youngn]

Ventures - read this whole study and you will get a better idea of the whole process. http://www.nature.com/jid/journal/v128/n5/full/5701147a.html . Some of the proteins secreted by balding dermal papillas are similar to when a cell goes into necrosis. So it is certainly possible that lack of blood to the DP can cause the cells to start some sort of apoptosis and the genetic structure then changes. At which point the standard growth signaling (via androgens) is retarded.

 

[Ventures]

Thanks very much for response, youngn. Anyway I found this picture which explains difference between safe and donor zone.