17 Jun 2002
The development of vertebrate brains is understood a little better now, following a three-dimensional confocal microscopy study to image axon growth in tadpoles. Axons connect brain cells, creating a communication network and building its structure.
Using a confocal microscope from the UK's Bio-Rad Microscience, researchers at the University of Melbourne in Australia followed the development of NOC-2+ tadpole brains exposed to the growth chemical chondroitin sulfate.
In tadpoles exposed to this chemical, fluorescent images showed abnormal brain development (see images), suggesting that chondroitin sulfate affects NOC-2+ axon formation in some fashion. One theory is that the chemical provides navigational cues.
Using the confocal microscope, 50 micron-thick optical "slices" of the developing brain were first imaged separately, and then mounted together and viewed as a single montage. In this way, brain development could be followed in vivo, whereas most studies of this kind are conducted in vitro.
Two chemicals were used to label the NOC-2+ axon, one the NOC-2 antibody, producing red fluorescence and the other acetylated a-tubulin, which emits green light. Where the two labels are both present, a yellow emission is seen (as in the bottom two panels).
From the data, the Australian team concluded that molecules binding to chondroitin sulfate act as pathfinders for the brain-building axons, although the precise nature of these molecular guides remains unknown.
Story courtesy of Opto and Laser Europe magazine