A low magnification photomicrograph of a section through a mouse dorsal root ganglion. The section has been processed to visualize neurons (white circles) that contain the enzyme thiamine monophosphatase (TMP). The coloring of the image has been inverted. The majority of these neurons are small and are involved in pain signaling. The lab is interested in these neurons because of their role in pain and their reliance on the neurotrophic factor GDNF.