RJ Edwards Lab 5: NerveHistology Notes 9/9/16

Nervous system Anatomical division: Central – Peripheral NS Functional division: Somatic – Autonomic NS Autonomic:

o Sympathetic: Epi, NorEpi, flight/fighto Parasympathetic: ACho Enteric: Auerbach’s and Meissner’s Plexi

Key cells types Neurons

o Large cells (20-50 µm)o large nucleus , prominent bulls-eye nucleolus

Neuroglia = support cellso CNS: Oligodendrocytes, astrocytes, microglia,

ependymal cellso PNS: Schwann cells, satellite cells, etc

CNS Brain

o Outer layer = gray mattero Inner layer = white matter

Spinal cord (reversed)o Outer layer = white mattero Inner layer = gray matter (butterfly)

Nerve (Microscopic) A fascicle of wavy fibers = neuronal axons Surrounded by a perineurium = key feature

o Several layers of flattened cellso Tight junctions, forms blood-nerve barrier

± Myelin sheaths = Schwann cells = bagel or donut Myelin = lipid-rich = extracted = white in slides Endoneurium = scant CT + capillaries

Nerve (Anatomic) A bundle of several nerve fascicles Surrounded by an epineurium (DICT with blood vessels)

Ganglion Nerve cell bodies (neurons) + nerve fibers (± myelin) Satellite cells = Perineurium

VocabularyNerve –vs– nerve fascicle –vs– nerve fiber –vs– neuronEpineurium, perineurium, endoneuriumBlood-Nerve BarrierGanglionNeuropilAxon, dendrite, hillock

Look-alikes: Nerve – Connective tissue – Smooth muscle In a well-preserved thin section, these three tissues are unmistakable, but… In a poorly-preserved, or thick section, these three fibrous tissues can be confused

o Look for perineurium &/or myelin ghosts = key distinguishing features (nerve)o Look for neuronal cell bodies & satellite cells (nerve ganglion)o Look for varying sized fibers, with nuclei outside fibers (CT)o Look for nuclei inside fibers and check appearance of SmM in blood vessels (SmM)

The Scream, 1893, by Edvard MunchThe Scream, 1893, by Edvard Munch