Nervous tissue histology Flashcards
What originates from the Pacinian Corpuscle? What does it do?
The distal process of the dorsal root ganglion neuron. Relays signals from the CNS when pressure upon the skin mechanically stimulates the receptor.
What is the grey matter composed of?
Neurons and supporting cells
What is the white matter composed of?
Myelinated axons
What is the neuropil?
The region of grey matter between cell bodies composed principally of dendrites and axons.
What does the Nissl stain elucidate?
Neuronal cell bodies of grey matter
How do neuronal cell bodies appear on histology?
Round euchromatic nucleus and dark nucleolus
What are Nissl bodies?
Rough ER and free ribosomes in neuronal cytoplasm extending into the bases of dendrites.
What are interneurons?
Small neurons that exist solely in the CNS for interneuronal communication
What are oligodendrocytes?
Supporting cells responsible for elaborating myelin in the CNS. Can be found in white matter.
What cells make myelin in the periphery?
Schwann cells
What is the endoneurium?
Fine reticular fibers that separate individual nerve fibers from one another.
What is a fascicle and what surrounds it?
A fascicle is a bundle of nerve fibers held together by a dense sheath called a perineurium.
What is the epineurium?
Connective tissue that loosely bundles together fascicles. This kind of bundle is what you’ll dissect in GA.
Describe nerve fibers in the parasympathetic ganglia.
Cell bodies are more irregular in shape
Soma usually smaller
Nerve fibers in the bundles between the ganglia are unmyelinated or thinly myelinated.
What cells do neural crest cells become during development?
Neurons, Schwann cells, and satellite cells of the PNS.
What is a major difference between CNS and PNS?
CNS lacks connective tissue
What is the perikaryon?
Rough ER, the cisternae of which are grouped and studded with polyribosomes. Labeled as Nissl bodies as the stain like basophilic clumps under LM.
Each node of Ranvier is associated with a _____ cell.
Schwann
What are dendritic spines? How do they vary?
Focal evaginations of the dendrite and serve as the main receptive structures for axon terminals. Neurons can have many (spinous), some (sparse), or none (aspinous).
What exists in axonal cytoplasm?
Mitochondria, microtubules, neurofilaments NO RIBOSOMES OR RER!
What part of a neuron contains neurotransmitters?
At ends: terminal boutons
Along the length: boutons en passant
What % of neurons in the PNS are surrounded by Scwann cells in one form or another?
ALL!
What are spinal nerves composed of?
Distal to the spinal cord dorsal and ventral roots merge forming “spinal nerves” and thus contain both sensory and motor nerves.
Sympathetic ganglia are positioned close to the _______ (____________) whereas parasympathetic ganglia are located close to, or within, the _______.
spinal cord (paravertebral ganglia),
target structure
