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michael barry said:Bryan,
This is a question for you and it should clear everything up for me, (cant believe Ive never thought to ask this of you). When androgens are added to hair cells experimentally from the Male Pattern Bald area in experiments, do the results differ from androgens added to hair cells culled from the hippocratic wreath area?
Michael, the answer is YES, and I'm a bit surprised that you don't already know all about that, because it's an issue that Stephen and I have already gone around and around over for quite a long time.
An excellent study which investigated that in a novel fashion (and since then, there's been at least one similar Japanese study which got the same results) is the much-discussed "Inhibition of Hair Growth by Testosterone in the Presence of Dermal Papilla Cells from the Frontal Bald Scalp of the Postpubertal Stumptailed Macaque", Uno et al, Endocrinology 138: 356-361. 1997. The big, important finding that came out of that study is that the hair-growth inhibition from androgens appears to be mediated through the dermal papilla. Androgens affect dermal papillae directly, and stimulate them to release either growth enhancers or growth repressors (depending on the genetic programming within a given follicle), which then migrate to the rest of the follicular structure and modify its overall growth accordingly. They showed that when dermal papillae from the balding areas of stumptailed macaques are co-cultured with epithelial cells and testosterone is added, the growth of the epithelial cells is strongly inhibited. However, testosterone added to a cell culture of those epithelial cells alone has no effect on their growth! In other words, the effect is coming by way of the dermal papilla. Furthermore, addition of testosterone to a co-culture of epithelial cells with dermal papillae from occipital follicles has no effect on the growth of the epithelial cells. I think that's a pretty damned clear indication of a key step in the balding process! :wink:
michael barry said:If the results are different in these experiments (i.e. slowing of the cell division of root sheath, keratinocytes, epithileal, etc....) that pretty much proves beyond any doubt that some innate genetic difference between these hairs exists (other than extra androgen receptors on the male pattern baldness hairs and being located in parts of the scalp that produce more alpha 5).
That, if affirmative, would end all alternative explanations other than the direct theory.
Guess what, Michael, our friend Stephen Foote even has a goofy explanation for THAT study, believe it or not! After my beating him over the head with it for a period of time, he put on his thinking-cap and came up with the following marvelously ad hoc rationalization:
Ok, so maybe hair follicles are indeed directly affected by androgens to some degree (he ruefully admits) , but it's still "edema" and "contact inhibition" which actually CAUSE them to become sensitive to those androgens in the first place!
I'm not kidding! The preceding is what he actually believes!!! I think you can see now why after so many years of ad hoc excuses and rationalizations, it's hard for very many of us to take his theory seriously. No matter what evidence is cited, he just keeps trying to turn it back around on "contact inhibition".
Bryan