Brain pigment

Sandra L Wegert sandraw at U.Arizona.EDU
Fri Oct 20 22:41:48 EST 1995


On Thu, 19 Oct 1995, Steve Rogers wrote:

> Hi.  Can anyone explain why certain brain structures (e.g. substantia
> nigra) contain the black pigment, melanin?  Thanks in advance.
> 
> ****************************************************
> Steve Rogers
> Dept. of Cell & Structural Biology and the
> Beckman Institute - Optical Visualization Facility
> Univ. of Illinois @ C-U
> srogers at delphi.beckman.uiuc.edu
> ****************************************************
 These are guesses based on something I read a long time ago, but forgot 
where:  
1) Before mammals had a thick skull, light entered the brain, and there 
were pigmented sensory structures there that detected light and used that 
light info to synchronize diurnal rythyms.  The pineal has been called 
the third eye for this reason in fish (I think).
2) Maybe melanin is a by-product of dopamine production or melatonin 
production.
3) It could be structural (but I doubt it).  Pigments are sometimes used 
to give strength to body parts, I've seen pigment cells wrapped around 
arterioles in lower vertebrates for this reason, and bird primary 
feathers are almost always strengthened by the presence of melanin.

A very interesting question; please post here if you get an answer.
Sandra



----------------------
sandraw at U.Arizona.EDU




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