Before beginning the study of the slides for this lab, examine the preserved-mounted specimens of CNS and PNS tissue, noting especially the gross or macroscopic appearance of the tissues (cerebrum, cerebellum, meninges, perineurium, etc.). The bigger view will give you a heads up on what you will be looking for on the slides.

Cells and general organization of the Central Nervous System (CNS)

• Looking at slide 112 and slide 125, and preserved-mounted specimens with the eye alone, note the difference between white and gray matter.
• Then examine a section of the cerebral cortex (slide 112) and identify
  • neuropil,
  • neurons,
  • oligodendrocytes, and
  • astrocytes (Fig. 9-9).
• Study the diagram of neurons (Fig. 9-3).
  • On slide 112, identify nucleoli and chromatophilic Nissl substance in neurons and understand their significance.

Why is a third type of glial cell, the microglial cell, relatively rare?

On the cerebral cortex section of slide 112, examine the edge showing remnants of the innermost meningial layer (pia mater) and note the intracerebral penetration of blood vessels from this surface. Compare this with a similar area of vessel penetration into the spinal cord as shown in Fig. 9-18.

Pia mater covers arteries and veins in the brain. Other components of the meninges are the arachnoid and the dura (Fig. 9-19). Note their interrelationship in the diagram.

Clinical note:  The meninges are the site of various medical problems, such as meningitis, subdural hematomas, subarachnoid hemorrhage, and meningiomas.

Cerebellum and spinal cord.