You can perfuse or distend the lung with diluted OCT.  Dilute it
approx 1:1 with PBS, inject through the trachea or large air passage,
using a syringe with a large bore needle, say a 19 gauge or so.

Use just a few mls, approx 3 mls, inject slowly, and watch the lung
expand.  Whatever you do, do not overfill or alveoli will be blown
away, then embed in OCT, and snap freeze.  I use a dry ice/isopentane slurry
to keep OCT from shattering with direct liq nitrogen freeze.  You can
always double embed in OCT after initial snap freeze, in a mold.

Be sure you do this perfusion/snap freeze quickly as the PBS tends to leak.
I would use a CO2 euthansia, possibly bleed out rat via veins and arteries
at base of spine to prevent any blood leaking into the lung.  You can also
clamp off arteries/veins from heart with a mosquito hemostat.

I also have a method from a lady who was an expert at this, slowmail
address please and I will send a copy.  Her method is even more elegant than
mine, and wonderfully done.

Gayle Callis