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SUMMARY:New Functions for Glial Cells: From Soft Guideposts for Neuronal M
 igration to Living Light Guides in the Retina - Kristian Franze from the U
 niversity of Leipzig
DTSTART:20070212T140000Z
DTEND:20070212T153000Z
UID:TALK6608@talks.cam.ac.uk
CONTACT:Alison Lord
DESCRIPTION:The nervous system consists of neurons and glial cells. It is 
 commonly thought that glial cells provide mechanical support for neurons. 
 In contrast\, we found that glial cells are in fact significantly softer t
 han all other surrounding cellular structures and rather act as shock abso
 rbers. We also found that in vitro neurons actively probe their mechanical
  environment. They retract their processes and re-extend them randomly whe
 n mechanical stresses exceeding ~300 Pa oppose their leading edge. Interes
 tingly\, glial cell processes are softer than 300 Pa and neurons attach to
  them during migration to precisely follow the glia processes\, even when 
 they are considerably bent. This suggests that the mechanical properties o
 f glial cells may facilitate and direct neuronal migration in the developi
 ng brain.\nOther glial cells in the CNS are also observed to perform highl
 y specialized functions\, such as Müller cells in vertebrate retinae. Whi
 le cells are mostly transparent\, they are phase objects that differ in sh
 ape and refractive index. Any image that is projected through layers of ce
 lls will normally be distorted by refraction\, reflection\, and scattering
 . Counter-intuitively\, the retina of the vertebrate eye is inverted and l
 ight must pass through several tissue layers before reaching the light-det
 ecting photoreceptor cells. We investigated the optical properties of reti
 nal tissue and individual Müller cells\, which are glial cells spanning t
 he entire thickness of the retina. We found that these cells amazingly act
  as optical fibers and guide light from the retinal surface to the photore
 ceptor cells. Their parallel arrangement in the retina is highly reminisce
 nt of fiber-optic plates used for low-distortion image transfer. Thus\, M
 üller cells seem to transfer images through the vertebrate retina with mi
 nimal distortion and low loss. This finding explains a fundamental feature
  of the inverted retina as an optical system\, and it ascribes another com
 pletely new kind of function to glial cells.\n\n
LOCATION:IRC in Superconductivity Seminar Room\, Cavendish Laboratory
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