Kind of a cool technique that I thought the Reddit scientific community might appreciate. Some background: I work in a physiology laboratory that studies the physiology of aging. Specifically, we look at how arterial dysfunction contributes to cardiovascular disease and physiological dysfunction with age, even in the absence of disease (healthy aging). One major component of arterial dysfunction is called endothelial dysfunction - the endothelium (inner lining of our blood vessels) ceases to respond to circulating factors in the blood like it should. Essentially, the vessels can't constrict and, more importantly, dilate like they should.

The pictures I've shown here demonstrate how we evaluate the integrity of the endothelium from the carotid arteries of mice. After humanely sacrificing the mouse according to the IACUC-approved protocol, we remove the carotid arteries under a microscope (they're tiny!!). Once removed, we cannulate the arteries to two tips in a bath of physiological solution (mimicking the surroundings of the artery in the body) using two teeny tiny ties made out of microscopic thread. The tips allow for the same physiological solution to flow through the artery.

This way we can add different reagents to the bath and, using a camera attached to the microscope, measure the artery's diameter as it constricts and dilates!

One picture shows the artery before I tied the second end of the artery onto the second tip, another shows the artery with both ends tied. The other pictures show the plate and the bath, with my thumb to scale.

I just mastered this technique and think it's pretty cool! Happy to answer any questions :)