Today I began my second week at the National Toxicology Program with Dr. Malarkey, or the pathology group. Grace Goetz also ventured to the National Institute of Environmental Health Sciences to join us. Early in the day, Dr. Malarkey showed Grace and I his shelf of interesting medical items that he has collected over his life. His collected contained memorabilia ranging from the first microscope he was given as a child to a 19th century copy of a veterinary manual title Diseases in Large Animals. It was mostly about cows.
Later, Dr. Malarkey obtained one of the microscopes previously by a postdoctoral fellow for me to use so I could review histopathology slides on my own. Dr. Malarkey handed me a couple of organ slices from the tissue of an eye and asked me to identify the different components of the eye, the different lesions, and the location and type of tumors. After a while of switching between the microscope and the internet, I was able to identify the iris, lens, cornea optic nerve, retina, cornea, vitreous humor of the eye. With the help of Dr. Malarkey, I located melanoma, a tumor commonly found in the skin, near the near the lens of the eye. Because of the melanoma, the iris and retina of the eye were folded and rendered inoperable. I also located a separate tumor that resulted in unbounded muscle growth besides the optic nerve and cataracts under the lens epithelium. I then headed to the ten-headed with microscopes to look at some brain slices with a variety of cancers, known as neuroglial neoplasms. Glioma is name for a brain cell that falls into a miscellaneous category, other cells are ependymal cells, astrocytes, oligodendrocytes, microglia, and Schwann cells. Each cell can also cause a unique cancer where that cell has unbounded reproduction, for example astrocytes can cause astrocytoma and oligodendrocytes can cause oligodendroglioma. Dr. Malarkey also explained the immunohistochemistry used to visualize different tumors. Once a tumor cell type has been identified, antibodies with dye are splashed over the cell that attach to a certain protein prevalent in the cancerous cell. The loose dye is then washed away, leaving only the proteins in the tumor with dye, thus visualizing the cancerous areas. We specifically looked at an example of a brain histopathology slide with a malignant glioma, and the protein S100. If the cell contained S100, the brown dye would remain, and if it didn’t the dye would wash away. Grace and I also got a chance to explore the necropsy lab, where the dissections take place.
An electron microscope!