Neuroembryology and Development of the Nervous System

Author(s):  
Eduardo E. Benarroch ◽  
Jeremy K. Cutsforth-Gregory ◽  
Kelly D. Flemming

The study of neuroscience begins with a survey of the embryonic development of the nervous system because it provides a framework and background for understanding the anatomy and function of the nervous system in the adult. The eventual location and connectivity of the structures in the brain, spinal cord, and peripheral nervous system reflect the orderly development of the nervous system.

2019 ◽  
Vol 48 (1) ◽  
pp. 10-18 ◽  
Author(s):  
Mark T. Butt

Many preclinical investigations limit the evaluation of the peripheral nervous system (PNS) to paraffin-embedded sections/hematoxylin and eosin–stained sections of the sciatic nerve. This limitation ignores several key mechanisms of toxicity and anatomic differences that may interfere with an accurate assessment of test article effects on the neurons/neurites peripheral to the brain and spinal cord. Ganglion neurons may be exposed to higher concentrations of the test article as compared to neurons in the brain or spinal cord due to differences in capillary permeability. Many peripheral neuropathies are length-dependent, meaning distal nerves may show morphological changes before they are evident in the mid-sciatic nerve. Paraffin-embedded nerves are not optimal to assess myelin changes, notably those leading to demyelination. Differentiating between axonal or myelin degeneration may not be possible from the examination of paraffin-embedded sections. A sampling strategy more consistent with known mechanisms of toxicity, atraumatic harvest of tissues, optimized fixation, and the use of resin and paraffin-embedded sections will greatly enhance the pathologist’s ability to observe and characterize effects in the PNS.


Author(s):  
Peggy Mason

The primary regions and principal functions of the central nervous system are introduced through the story of Jean-Dominique Bauby who became locked in after suffering a brainstem stroke. Bauby blinked out his story of locked-in syndrome one letter at a time. The primary deficit of locked-in syndrome is in voluntary movement because pathways from the brain to motoneurons in the brainstem and spinal cord are interrupted. Perception is also disturbed as pathways responsible for transforming sensory stimuli into conscious awareness are interrupted as they ascend through the brainstem into the forebrain. Homeostasis, through which the brain keeps the body alive, is also adversely affected in locked-in syndrome because it depends on the brain, spinal cord and autonomic nervous system. Abstract functions such as memory, language, and emotion depend fully on the forebrain and are intact in locked-in syndrome, as clearly evidenced by Bauby’s eloquent words.


Author(s):  
Daniel J. Wallace ◽  
Janice Brock Wallace

A fibromyalgia patient frequently complains of pain. The pain of fibromyalgia is different from that of a headache, stomach cramp, toothache, or swollen joint. It has been described as a type of stiffness or aching, often associated with spasm. Unlike the other pains mentioned above, fibromyalgia pain responds poorly to aspirin, acetaminophen (Tylenol), or ibuprofen (Advil, Motrin). In fact, studies have suggested that even narcotics such as morphine are minimally beneficial in ameliorating fibromyalgia pain. Why is it that fibromyalgia patients can take codeine, Darvon, Vicodin, or even Demerol for musculoskeletal aches and have only a slight response? What produces “pain without purpose”? In this chapter, we’ll explore what makes fibromyalgia a pain amplification syndrome. Why does the patient hurt in places where there was often no injury and all laboratory tests are normal? What creates what doctors call allodynia, or a clinical situation that results in pain from a stimulus (such as light touch) that normally should not be painful? Fibromyalgia is a form of chronic, widespread allodynia, as well as sustained hyperalgesia, or greater sensitivity than would be expected to an adverse stimulus. The nervous system consists of several components. The brain and spinal cord comprise the central nervous system. Nerves leaving the spinal cord that tell us to move our arms or legs are part of the “motor” aspects of the peripheral nervous system. Additionally, all sorts of information about touch, taste, chemicals, and pressure are relayed through “sensory” pathways back to the spinal cord, where they are processed and sent up to the brain for a response. The autonomic nervous system consists of specialized peripheral nerves. Fibromyalgia is a disorder characterized by an inappropriate neuromuscular reaction that leads to chronic pain. Patients with fibromyalgia usually react normally to acute pain. Our current concepts of the way the body responds to chronic painful stimuli stem from the gate theory, first proposed by Ronald Melzack and Patrick Wall in 1965. Nerve “wires” go from the periphery to the dorsal horn of the spinal cord. These wires are modulated by feedback loops within the nervous system.


Author(s):  
M Dlamini

The spinal cord is the primary pathway of communication between the brain and peripheral nervous system. Knowledge of the spinal cord anatomy and recognition of typical common spinal cord syndromes are important as many of these diseases have a predilection for targeting specific areas or tracts within the spinal cord.


2016 ◽  
Vol 8 (337) ◽  
pp. 337rv5-337rv5 ◽  
Author(s):  
Kate L. Montgomery ◽  
Shrivats M. Iyer ◽  
Amelia J. Christensen ◽  
Karl Deisseroth ◽  
Scott L. Delp

2021 ◽  
pp. 996-1008
Author(s):  
Michel Toledano ◽  
Allen J. Aksamit Jr

Viruses may cause acute, subacute, or, rarely, chronic infection of the nervous system. The most common acute syndromes of nervous system infections are meningitis and encephalitis, but viruses can also affect the spinal cord and the peripheral nervous system. Viruses can be classified in many ways. One classification scheme assesses the type of nucleic acid (DNA or RNA), whether it is double or single stranded, its sense, and its method of replication.


2020 ◽  
Vol VI (2) ◽  
pp. 139-154
Author(s):  
A. A. Tsvetaev

A positive answer to this topic was given in 1882 by prof. N. M. Popov in his dissertation: "Materials for science on acute mellitic toxic origin". He asserts that, first of all, the nerve cells (of the spinal cord) come to a state of turbid swelling and vacuolization. Both of these processes can lead them to complete destruction: the first, through the transition to a bland, spreading formation, the second, through an increase in the vacuole. Finally, in the late period, there is a pigment atrophy, which destroys all the cells, the improvement from the previous changes. The intensity of the process is determined by the greater or lesser proximity of the vessel .... In all likelihood, the author says, the brain also changes here. With the same positivity, the suffering of the peripheral nervous system is excluded in this work.


2020 ◽  
Vol 23 (9) ◽  
pp. 624-628
Author(s):  
Ahmadreza Afshar ◽  
Ali Tabrizi

This brief review presents Razi’s concepts of bone and joint disorders. Razi differentiated between ligaments, tendons, and nerves and recognized the role of the brain, spinal cord, and peripheral nervous system in the perception of senses and voluntary movements. He described paralysis and loss of sensation following brain, spinal cord, and peripheral nervous system injuries. Razi presented an early concept of compartment syndrome. Razi’s approach to fracture management is very similar to the current concept of functional bracing for some fractures. Razi mentioned suturing the wounds and ligation of bleeding large vessels. He cautioned about phlebotomy in the antecubital fossa as it may become complicated by the adjacent arterial and nerve injuries. Razi treated osteomyelitis by removing the infected and necrotic bone by sawing, cutting, and rasping. He also documented arthralgia, painful hip, and sciatic pain and made a sharp distinction between arthralgia and gout. He indicated the gout origin as the production of a waste substance that the body fails to expel. Razi’s basic concepts on the bone and joint disorders established a foundation for modern orthopedic science.


Author(s):  
S.S. Spicer ◽  
B.A. Schulte

Generation of monoclonal antibodies (MAbs) against tissue antigens has yielded several (VC1.1, HNK- 1, L2, 4F4 and anti-leu 7) which recognize the unique sugar epitope, glucuronyl 3-sulfate (Glc A3- SO4). In the central nervous system, these MAbs have demonstrated Glc A3-SO4 at the surface of neurons in the cerebral cortex, the cerebellum, the retina and other widespread regions of the brain.Here we describe the distribution of Glc A3-SO4 in the peripheral nervous system as determined by immunostaining with a MAb (VC 1.1) developed against antigen in the cat visual cortex. Outside the central nervous system, immunoreactivity was observed only in peripheral terminals of selected sensory nerves conducting transduction signals for touch, hearing, balance and taste. On the glassy membrane of the sinus hair in murine nasal skin, just deep to the ringwurt, VC 1.1 delineated an intensely stained, plaque-like area (Fig. 1). This previously unrecognized structure of the nasal vibrissae presumably serves as a tactile end organ and to our knowledge is not demonstrable by means other than its selective immunopositivity with VC1.1 and its appearance as a densely fibrillar area in H&E stained sections.


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