Fig 2.

Four sections of an anatomicspecimen stained by the Perls method shows the blue stain revealing iron-rich regions. Sections have been counterstained by using neutral red. The contours of cerebral regions have been traced by using the counterstaining of the Perls stained section and Nissl staining of the adjacent sections. Note that the Perls reaction is positive in the anterior portion of the subthalamic nucleus (posterior commissure, +12.4 mm) but very weak in its posterior portion (posterior commissure, +7.3 mm).