Summary of Observations

This is a coronal cut from the caudal medullary region of a mouse brain. The section is 50mm thick, cut by freezing microtome, and it is Nissl stained. The Nissl method highlights differentiation in neurons and bodies by staining RNA. Cresyl violet, the Nissl stain used, colors cell bodies and glia a deep violet. This section presents the central canal rather evidently. Also, notice the concentration of large motor neurons in the hypoglossal nucleus. Next, the decussation of the pyramidal tract where cortico-spinal fibers cross over to the contralateral side of the medulla is also rather clear. More ambiguous however are the laminations in the dorsal horn. Ventral to these laminations is the spinal trigeminal nucleus which receives sensory information (including pain) from the ipsilateral half of the face. On top of the caudal nucleus a trained eye can see a cap of substantia gelatinosa.