Figure 2

The distribution of C6 motor neurons. A: The dorsal view of the cervical spinal cord. The C6 spinal segment was defined as the area between the lower edge of the C5 dorsal rootlets and the upper edge of the C7 dorsal rootlets. Black arrows indicate the border. The dashed lines indicate the contour of the dorsal rootlets. B: In the coronal section of the ventral horn of the spinal cord, all hydroxystilbamidine-labeled motor neurons were distributed within the defined C6 segment. C: A transverse section of the C6 spinal segment. All hydroxystilbamidine-labeled motor neurons were distributed in the ventral horn. The white arrowhead indicates the motor neurons within the ventrolateral area and the white arrow indicates those within the ventromedial area. The dashed line indicates the border between the white and the gray matter. D: The area for motor neuron counting was defined as the area within the gray matter that is enclosed by the two dashed lines (Bar: 200 μm.).