TABLE 1.

Troubleshooting table.

Step	Problem	Possible reason(s)	Solution
EQUIPMENT SETUP	Inconsistent or unstable 02 tensions in the exposure chamber	Failure to deliver or maintain the set oxygen tension can result from faulty tanks and regulators, a leaking flowmeter, leaking connectors to tubing or mechanical failure of the analyzer pump	Check all connections in the system and tank regulators Replace faulty tanks and test the analyzer (pump) for performance
			Frequent monitoring (twice daily) will minimize such failures
			If a leak persists, check the gloved portholes and integrity of the sealing gaskets around the connecting door between the main chamber and the air-lock, and around the air-lock's exterior door
EQUIPMENT SETUP and Step 8	Failure to induce vascular remodeling	Rodents were incorrectly exposed to the set 02 tension	Keep strictly to the schedule described for the 02 tension and length of exposure for the high 02/air cycle
			If rat or mouse strains different from the ones described are used, check for reported differences in the 'angiogenic' response of different strains
10-16	Incomplete lung inflation with fixative	Cut in lung surface or pulmonary artery	(Typically) Discard the lung
		Poor placement and/or ligation of catheters, or bubbles or kinks in the fixative delivery line	If the lungs do not (visibly) begin to fill within the first 30 seconds, check the placement of each catheter and check if there are bubbles or kinks in the delivery lines. If nonfilled regions appear as fixative distends the lungs, gently move each lobe until all regions become well distended
25	Insufficient vessels or cells available for analysis	Blocks taken from regions too central and contain larger vascular/airway structures	Choose additional blocks or recut original blocks to attempt to expose other vessels deeper in the lung tissue
26-32	Lung tissue blocks embedded in Epon-araldite resin do not cut well	Air trapping in the lung or poor tissue dehydration, infiltration and polymerization steps	Poorly prepared blocks cannot be retrieved. Review all steps of the procedure and extend times in reagents. Blocks larger than the size (3 mm3) recommended will not process adequately for the procedure times listed. Check quality of the Histoknife or diamond knife
33-41	High levels of extraneous 'dirt' in the resolution images	Dirty knife boat, tools or reagents used for double-staining steps	Change water in knife boat between blocks Ensure tweezers and cutting tools used are clean Use freshly prepared reagents. Filter all reagents well and extend rinse times