Allen Ehrlicher,
Timo Betz,
Björn Stuhrmann,
Michael Gögler,
Daniel Koch,
Kristian Franze,
Yunbi Lu,
Josef Käs
Methods in Cell Biology
83
495-520
(2007)
| Journal
We present a novel technique to noninvasively control the growth and turning behavior of an extending neurite. A highly focused infrared laser, positioned at the leading edge of a neurite, has been found to induce extension/turning toward the beam's center. This technique has been used successfully to guide NG108-15 and PC12 cell lines [Ehrlicher, A., Betz, T., Stuhrmann, B., Koch, D. Milner, V. Raizen, M. G., and Kas, J. (2002). Guiding neuronal growth with light. Proc. Natl. Acad. Sci. USA 99, 16024-16028], as well as primary rat and mouse cortical neurons [Stuhrmann, B., Goegler, M., Betz, T., Ehrlicher, A., Koch, D., and Kas, J. (2005). Automated tracking and laser micromanipulation of cells. Rev. Sci. Instr. 76, 035105]. Optical guidance may eventually be used alone or with other methods for controlling neurite extension in both research and clinical applications.
Müller cells are living optical fibers in the vertebrate retina
Kristian Franze,
Jens Grosche,
Serguei N. Skatchkov,
Stefan Schinkinger,
Christian Foja,
Detlev Schlid,
Ortrud Uckermann,
Kort Travis,
Andreas Reichenbach, et al.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF
AMERICA
104
(20)
8287-8292
(2007)
| Journal
| PDF
Although biological cells are mostly transparent, they are phase objects that differ in shape and refractive index. Any image that is projected through layers of randomly oriented cells will normally be distorted by refraction, reflection, and scattering. Counterintuitively, the retina of the vertebrate eye is inverted with respect to its optical function and light must pass through several tissue layers before reaching the light-detecting photoreceptor cells. Here we report on the specific optical properties of glial cells present in the retina, which might contribute to optimize this apparently unfavorable situation. We investigated intact retinal tissue and individual Miller cells, which are radial glial cells spanning the entire retinal thickness. Muller cells have an extended funnel shape, a higher refractive index than their surrounding tissue, and are oriented along the direction of light propagation. Transmission and reflection confocal microscopy of retinal tissue in vitro and in vivo showed that these cells provide a low-scattering passage for light from the retinal surface to the photoreceptor cells. Using a modified dual-beam laser trap we could also demonstrate that individual Muller cells act as optical fibers. Furthermore, their parallel array in the retina is reminiscent of fiberoptic plates used for low-distortion image transfer. Thus, Miller cells seem to mediate the image transfer through the vertebrate retina with minimal distortion and low loss. This finding elucidates a fundamental feature of the inverted retina as an optical system and ascribes a new function to glial cells.
Contact
Neuronal Mechanics Division Prof. Kristian Franze Principal Investigator
Max-Planck-Zentrum für Physik und Medizin Kussmaulallee 2 91054 Erlangen, Germany
