Dear histoners,

I cannot do any perfusion of the blood vessels samples as I need an intact
endothelium for other kind of experiments. So, I only isolated the blood
vessels and froze it in liquid nitrogen. 

Yesterday, I did frozen section and found that there were much blood
inside the lumen. Two questions comes up:

1. Is it possible to get rid of the blood cells?
2. Is the preservation method (by freezing the samples in liquid
nitrogen) optimal to preservation the antigens on the endothelial cells so
I can use IHC to stain the endothelial cells?

Thank you very much!

Yours,
Circle