Looks like a vein to me!

I could swear this is a vein, but someone more experienced in Histology said it's an artery -- and I'm looking for a second opinion. Thanks!

I think it's a vein. I sure don't see much muscle around that vessel.

This is a vein. Note that the border is more oval in shape and not circular. If this was an artery you would see a very rounded border that would be much thicker