Using the foldscope, we examined fresh pus from a scab on one of our classmate’s knees. After examining and photographing the pus under the microscope, we thought it would be interesting to compare our image to an image of normal blood. We suspected that there might be some notable differences between the cells visible in pus vs. blood, and we were curious whether white or red blood cells would be distinguishable in the foldscope image. To perform this comparison, we were hoping for a nosebleed or accidental cut during our time with the foldscope, which would have allowed us to collect blood noninvasively. Unfortunately, none of us had a nosebleed or wound during the time span of which we had to conduct the project. It so happens, though, that we were blessed with another means for obtaining blood noninvasively: our menstrual cycles! Thus, we were able to sample period blood, and we examined it for comparison under the foldscope.

The image above is a sample of period blood. Doing some research online, we found that menstrual blood consists of the following components: blood, endometrium, and the unfertilized egg ( http://www.menstruation-info-with-doc.com/menstruation-blood.html ). Looking at the foldscope image, we can definitely see the small, circular, un-nucleated red blood cells. The clustering of larger, nucleated cells in the lower center of the image are perhaps cells of the sloughed-off endometrium. The unfertilized egg does not appear to be in this image, but the chances of capturing an image (or even collecting a sample) containing the egg are infinitesimally small.

When we compare the period blood to the pus, we see right away that the red blood cells that are prominent in the period blood image are not particularly visible in the pus, as we would have expected. Instead, here we see an agglomeration of larger, nucleated cells. Doing some searching online, we read that pus is an accumulation of dead leukocytes ( http://www.medicalnewstoday.com/articles/249182.php ). These leukocytes are possibly what we see here!

“I conducted this project as part of Professor Pringle’s EEB321 class at Princeton University”