We are currently using a BioRad MRC600 system to examine structure and
physiology of capillary blood vessels in the frog and hamster mesentery.  We
have various projects, among which are: 1) examination of the 3D orientation of
endothelial cells by observation of very light silver staining of the
endothelial cleft and 2) measurement of the temporal and spatial development of
solute diffusion gradients in tissue surrounding individually perfused
capillaries as well as capillary wall permeability coefficients.   (The latter
project is being done in the x-z plane with recording over time--so our three
dimensions are really x-z-t at present.)
  These projects are being done on live tissue.  We use measurements of
permeability before and after laser illumination to check for tissue
viability/damage.  Other significant points that we have investigated related
to the technology concern 1) the apparent elongation in z due to mismatch of
refractive indeces and 2) attenuation of fluorescent intensity with depth in
tissue.
 
Roger Adamson
Dept. Human Physiology
School of Medicine
Univ. Calif. Davis