All-optical histology using ultrashort laser pulses.
As a means to automate the three-dimensional histological analysis of brain tissue, we demonstrate the use of femtosecond laser pulses to iteratively cut and image fixed as well as fresh tissue. Cuts are accomplished with 1 to 10 microJ pulses to ablate tissue with micron precision. We show that the permeability, immunoreactivity, and optical clarity of the tissue is retained after pulsed laser cutting. Further, samples from transgenic mice that express fluorescent proteins retained their fluorescence to within microns of the cut surface. Imaging of exogenous or endogenous fluorescent labels down to 100 microm or more below the cut surface is accomplished with 0.1 to 1 nJ pulses and conventional two-photon laser scanning microscopy. In one example, labeled projection neurons within the full extent of a neocortical column were visualized with micron resolution. In a second example, the microvasculature within a block of neocortex was measured and reconstructed with micron resolution.
Tsai
Philbert S
PS
Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA.
Friedman
Beth
B
Ifarraguerri
Agustin I
AI
Thompson
Beverly D
BD
Lev-Ram
Varda
V
Schaffer
Chris B
CB
Xiong
Qing
Q
Tsien
Roger Y
RY
Squier
Jeffrey A
JA
Kleinfeld
David
D
D000818:Animals; D000831:Animals, Newborn; D016477:Artifacts; D005260:Female; D016591:Histocytological Preparation Techniques / Q000295:instrumentation / Q000379:methods*; D007150:Immunohistochemistry; D007834:Lasers; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D018613:Microscopy, Confocal / Q000295:instrumentation / Q000379:methods*; D019579:Neocortex / Q000378:metabolism / Q000648:ultrastructure; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure; D051381:Rats