Tuesday, November 4, 2008


Twelve biology students took a field trip with Mr. Hermanson to the electron microscope facility at the Dartmouth Medical School. Rachel Finlayson, class of 2012, writes:

Sooner than I thought, it was Thursday, and we left at 12:15 sharp. The facility was largely concrete and all sound was slightly muffled. As we passed by doors leading to classrooms, we occasionally saw students and teachers in lab coats performing experiments, or signs saying "Caution: Radioactive Materials!" This was the real thing! After walking down several hallways, we met up with the head of the department (Dr. Daghlian) and Dr. Howard. Our group was split in two; half were to go to see the scanning electron microscope, and the rest were to go see the transmission electron microscope.

My group first learned about Dartmouth’s scanning electron microscope (top photo). Dr. Daghlian explained that the SEM shoots an electron beam down on a specimen, enabling one to see the surface of a cell. After the beam bounces off the specimen in a certain pattern, it is interpreted by the Scanning Electron Microscope and projected in live feed. My question, why Electron Microscopes are better than light microscopes, was quickly answered: certain things are too small to see by light, and light just doesn't show the same precision for small things that electrons do. To my disappointment, you cannot see electrons with the SEM. However, you can see Mycoplasms (tiny tiny bacteria), viruses, proteins, lipids, the list goes on.
After about half an hour we switched groups and followed Dr. Howard into a dimly-lit room full of plastic and machinery. A glowing green light showed us where the transmission electron microscope’s stage was. (The photo shows Spencer Hardy, class of 2012, working with this microscope.) TEMs are used to see inside cells and study their interior makeup. In some ways, it can be compared to a light microscope. TEMs work by focusing a beam of electrons through the specimen, just like light microscopes send beams of light through specimens. However, instead of using glass, which can be faulty in some cases (I have learned), TEMs use electromagnets to direct the beam of electrons.

The EM Facility can be used by most people at Dartmouth: the faculty, staff and students. The DHMC staff also comes here to do research, I learned. The facility is meant to provide service to anyone who needs it, but it does have limited faculty; anyone who wishes to use the Electron Microscopes has to sign up for a specific time slot at $35 an hour. Usually, one does one's own microscopy unsupervised, so it a good idea to sign up for some training! Two or three people are usually trained at a time. Of course, anyone wishing to use the Dartmouth EM Facility must be okayed by the Facility Director in order to protect the instruments from possible damage. They cost about a million dollars!

My visit to the Charles Gilman Life Sciences Lab really had me considering being a scientist as a job. It was absolutely fascinating!