Lab 1 Nervous Tissue Histology Flashcards
a neuron consists of:
A perikaryon (cell body)
One Axon
Number of dendrites
Perikaryon consists of
Cell nucleus
Cytoplasm surrounding nucleus Nissl Substance
Unipolar (pseudo unipolar) neuron
Sensory neuron with cell bodies in spinal and cranial nerve ganglia
Originate embryologically as bipolar neurons
Bipolar neuron
Relatively rare
Sensory neurons found in:
olfactory epithelium
Retina of the eye
Ganglia of the vestibulocochlear nerve
Multipolar neuron
Most common type
Located:
In CNS
In autonomic ganglia
Have more than 2 processes emanating from the cell body
Cerebellar cortex
Superficial grey matter of the cerebellum
Three layers of the cerebellar cortex
Outer molecular layer made of few cells and many no myelinated fibers
Intermediate layer made of Purkinje cells
Inner granular layer made of tightly packed cells and fibers
2 characteristics of multipolar neurons
More than two processes from the cell body
Cell body received synaptic input just like the dendrite receives
Axon is specialized to do what?
Conduct excitation from the input region to the output region of a neuron
Dendritic Zone =
Cell body plus the dendrites of a multipolar cell
Telodendria
Axon terminal branches
Neuroglial cells are
Supportive cells of the nervous tissue
Astrocytes:
Provide structural support for the CNS
Oligodendria:
Form myelin in the CNS
Microglia:
Serve as a macrophage in the CNS
Fibrous astrocytes
Found in white matter
Long, slender processes
Protoplasmic astrocytes
Found in grey matter
Short, bushy processes
Astrocyte end feet:
Contact blood vessels and control local blood flow in the CNS
Cell bodies in white matter belong to:
Glial cells or blood vessels
Not neurons!
Astrocyte cell body:
Large, oval, leptochromatic nucleus
Oligodendrocyte cell body:
Small, round, pachychromatic nucleus
Microglia comprise ……. Of the glial cell population
4%, hard to find
…….. Surrounds individual nerve fascicles
Perineurium
………. Surrounds individual myelinated fibers within the fascicle
Endoneurium
……….. ……… Form a protective barrier around the nerve fascicle
Perineural epithelium
Myelin appears as ……. Following lipid extraction during processing
Neurokeratin
Myelinated axons are surrounded by:
Myelin sheath
Lemmocyte cytoplasm
…………. Are thin and blend with lemmocyte cytoplasm
Non myelinated fibers
3 things that are evident in looking at non myelinated fibers
High density of lemmocyte nuclei
Wavy pattern of nerve fibers
Connective tissue sheaths
Spinal cord features (4)
Central canal
Gray matter
White matter
Spinal roots and meninges
The central canal of the spinal cord is lined by
Ependymal cells
Projections of gray matter
Dorsal, ventral, and intermediate horns
Ventral horn neurons
Motor neurons
Dorsal horn neurons
Sensory
Multipolar neurons have: 3 things
Leptochromatic nucleus
Prominent Nucleolus
Nissl substance (RER)
Meninges surround
Brain
Spinal cord
Roots of peripheral nerves
layers of meninges
Pia mater
Arachnoid
Dura mater
Subarachnoid space contains
Lined by flat fibrocytes and contains cerebrospinal fluid
Spinal ganglion neurons are
Unipolar
Unipolar cell bodies are found in …….. And in ganglia on the roots of ……..
Spinal ganglia (on dorsal roots) Cranial nerves
Multipolar neurons (…….) are found in ……
Postganglionic autonomic neurons
Autonomic ganglia
Preganglionic autonomic neurons synapse on the postglanglionic neurons within ……
Autonomic ganglia
Perikarya of unipolar neurons are :
Large
Leptochromatic nucleus
Prominent Nucleolus
Nissl substance is fine and evenly dispersed
Individual perikarya are enclosed by a capsule of
Satellite cells (lemmocytes)
Receptors are
Sensory endings of peripheral branches of afferent (GSA & GVA) axons
Receptors function to
Convert environmental energy into nerve conduction signals
Morphologically some receptors are (2)
Free nerve endings
Or
Encapsulated by cells derived from lemmocytes and perineural epithelium
Pacinian corpuscle (aka….) consists of
Lamellar corpuscle
Large axon surrounded by concentric layers of flattened cells
Innermost cells are lemmocytes
Outer are perineural epithelium
Pacinian corpuscle responds to
Mechanical stimulation, particularly transient stimuli (vibration vs steady pressure)
