Schematic of polarized light microscopy system. A dissection stereomicroscope with a USB camera was mounted upside-down to a bench top. A fiber-optic ring light was attached to the motor housing providing a light source to the sample without hindrance from the motor. The polarizer was placed on top of the sample dish, and the analyzer was placed on the microscope as shown with the axis of polarization orthogonal to the axis for the polarizer. A small hole in the polarizer allowed free insertion and rotation of the acupuncture needle in the sample.