DOCSLIB.ORG

Laboratory Activity Histology for Student

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Laboratory Activity Histology for Student 1 LABORATORY ACTIVITY HISTOLOGY FOR STUDENT Module author : Dr. Wida Purbaningsih, dr., M.Kes Resource Person : Dr. Wida Purbaningsih, dr., M.Kes Subject : Nerve tissue Department : Histology A. Sequence I. Introduction : 40 min II. Pre Test : 5 min III. Activity Lab : 70 min - Discussion 20 min - Identify 50 min IV. Post Test : 5 min B. Topic 1. General microstructure of the neuron, neuroglia, and nerve tissue 2. General microstructure of the central nerve tissue (CNS) Cerebrum Cerebellum Medulla spinalis 3. Genral microstructure of the peripheral nerve tissue (PNS) C. Venue Biomedical Laboratory Faculty of Medicine, Bandung Islamic Universtity D. Equipment 1. Light microscopy 2. Stained tissue section : 1. Motor Neuron Neuron and neuroglia 2. Cerebrum/Cerebellum/Medulla spinalis 3. Cerebrum Nerve tissue Meningens 4. Cerebellum 5. Medulla spinalis 6. Ganglion otonom Peripheral Nerve 7. Ganglion Snesorik Tissue 8. Nervus ischiadicus 3. Colouring pencils E Pre-requisite - Before following the laboratory activity, the students must prepare : 1. Draw the schematic picture of neuron and give explanation 2. Mention four type of neuroglia and their functional (astrocyte, microglia, oligodendrosit, sel schwan, and ependymal cell), then draw the schematic neuroglia and give explanation 3. Draw the schematic picture of nerve tissue microsructure and give explanation 2 4. Draw the schematic picture of cerebrum microsructure and give explanation 5. Draw the schematic picture of cerebellum microstructure and give explanation 6. Draw the schematic picture medulla spinalis microstrusture and give explanation 7. Draw the schematic picture of meningens microstructure and give explanation about tissue type 8. Draw the schematic ganglion sensorik microstrusture and give explanation 9. Draw the schematic ganglion otonom microstrusture and give explanation. 10. Draw the schematic nervus (nerve fiber) microstrusture and give explanation - Content lab in manual book ( pre and post test will be taken from the manual, if scorring pre test less than 50, can not allowed thelab activity ) - Bring your text book, reference book e.q atlas of Histology, e-book etc. (minimal 1 group 1 atlas ). - Bring colouring pencils for drawing NERVE TISSUE The human nervous system, by far the most complex system in the body, is formed by a network of many billion nerve cells (neurons), all assisted by many more supporting cells called glial cells. Each neuron has hundreds of interconnections with other neurons, forming a very complex system for processing information and generating responses. Nerve tissue is distributed throughout the body as an integrated communications network.(Gartner 2017) Nervous tissue, comprising perhaps as many as a trillion neurons with multitudes of interconnections, forms the complex system of neuronal communication within the body. Certain neurons have receptors, elaborated on their terminals, that are specialized for receiving different types of stimuli (e.g., mechanical, chemical, thermal) and transducing them into nerve impulses that may eventually be conducted to nerve centers. These impulses are then transferred to other neurons for processing.(Mescher 2018) The nervous system develops from the ectoderm of the embryo in response to signaling molecules from the notochord (Gartner 2017). Cells of the nervous system are classified into two categories: neurons and neuroglia. Neurons are responsible for the receptive, integrative, and motor functions of the nervous system. Neuroglial cells are responsible for supporting, protecting, and assisting neurons in neural transmission. I. NEURONS The cells responsible for the reception and transmission of nerve impulses to and from the CNS are the neurons. Ranging in diameter from 5 to 150 μm, neurons are among both the smallest and the largest cells in the body. Most neurons are composed of three distinct parts: o A cell body (perikaryon or soma): the central portion of the cell where the nucleus and perinuclear cytoplasm are contained. o multiple dendrites, which are the numerous elongated processes extending from the perikaryon and specialized to receive stimuli from other neurons at unique sites called 3 synapses. Dendrites processes specialized for receiving stimuli from sensory cells, axons, and other neurons o a single axon. which is a single long process ending at synapses specialized to generate and conduct nerve impulses to other cells (eg, nerve, muscle, and gland cells). Axons may also receive information from other neurons, information that mainly modifies the transmission of action potentials to those neurons. Axon have varying diameter and up to 100 cm in length (Gartner 2017). o Nerve Impulses o Synaptic Communication Generally, neurons in the CNS are polygonal (Fig. 1.a), with concave surfaces between the many cell processes, whereas neurons in the dorsal root ganglion (a sensory ganglion of the PNS) have a round cell body from which only one process exits (Fig. 1.c). Cell bodies exhibit different sizes and shapes that are characteristic for their type and location. Figure 1. Shown are the four main types of neurons, with short descriptions. (a) Most neurons, including all motor neurons and CNS interneurons, are multipolar. (b) Bipolar neurons include sensory neurons of the retina, olfactory mucosa, and inner ear. (c) All other sensory neurons are unipolar or pseudounipolar. (d) Anaxonic neurons of the CNS lack true axons and do not produce action potentials, but regulate local electrical changes of adjacent neurons. I.1 Cell Body (Perikaryon or Soma) The neuronal cell body contains the nucleus and surrounding cytoplasm, exclusive of the cell processes (Figure 4–a and b). It acts as a trophic center, producing most cytoplasm for the processes. Most cell bodies are in contact with a great number of nerve endings conveying excitatory or inhibitory stimuli generated in other neurons. A typical neuron has an unusually large, euchromatic nucleus with a prominent nucleolus, indicating intense synthetic activity. Cytoplasm of perikarya often contains numerous free polyribosomes and highly developed RER, indicating active production of both cytoskeletal proteins and proteins for transport and secretion. Histologically these regions with concentrated RER and other 4 polysomes are basophilic and are distinguished as chromatophilic substance (or Nissl substance, Nissl bodies) (Figure 4-a and b). The amount of this material varies with the type and functional state of the neuron and is particularly abundant in large nerve cells such as motor neurons (Figure 4–a and b). The Golgi apparatus is located only in the cell body, but mitochondria can be found throughout the cell and are usually abundant in the axon terminals. In both perikarya and processes microtubules, actin filaments and intermediate filaments are abundant, with the latter formed by unique protein subunits and called neurofilaments in this cell type. Cross-linked with certain fixatives and impregnated with silver stains, neurofilaments are also referred to as neurofibrils by light microscopists. Some nerve cell bodies also contain inclusions of pigmented material, such as lipofuscin, consisting of residual bodies left from lysosomal digestion. I.2 Dendrites Dendrites (Gr. dendron, tree) are typically short, small processes emerging and branching off the soma (Figure 2). Usually covered with many synapses, dendrites are the principal signal reception and processing sites on neurons. The large number and extensive arborization of dendrites allow a single neuron to receive and integrate signals from many other nerve cells. For example, up to 200,000 axonal endings can make functional contact with the dendrites of a single large Purkinje cell of the cerebellum. Dendrites become much thinner as they branch, with cytoskeletal elements predominating in these distal regions. In the CNS most synapses on dendrites occur on dendritic spines, which are dynamic membrane protrusions along the small dendritic branches, visualized with silver staining (Figure 2) and studied by confocal or electron microscopy. Dendritic spines serve as the initial processing sites for synaptic signals and occur in vast numbers, estimated to be on the order of 1014 for cells of the human cerebral cortex. Dendritic spine morphology depends on actin filaments and changes continuously as synaptic connections on neurons are modified. Changes in dendritic spines are of key importance in the constant changes of the neural plasticity that occurs during embryonic brain development and underlies adaptation, learning, and memory postnatally. 5 DS D D D CB Figure 2. The large Purkinje neuron in this silver-impregnated section of cerebellum has many dendrites (D) emerging from its cell body (CB) and forming branches. The small dendritic branches each have many tiny projecting dendritic spines (DS) spaced closely along their length, each of which is a site of a synapse with another neuron. Dendritic spines are highly dynamic, the number of synapses changing constantly. (X650; Silver stain) I.3 Axon Most neurons have only one axon, typically longer than its dendrites. Axonal processes vary in length and diameter according to the type of neuron. Axons of the motor neurons that innervate the foot muscles have lengths of nearly a meter; large cell bodies are required to maintain these axons, which contain most of such neurons’ cytoplasm. The plasma membrane of the axon is often called the axolemma and its contents are known as axoplasm (contains mitochondria, microtubules,
Load more

Recommended publications
  • The Neuron Label the Following Terms: Soma Axon Terminal Axon Dendrite
    The neuron Label the following terms: Soma Dendrite Schwaan cell Axon terminal Nucleus Myelin sheath Axon Node of Ranvier Neuron Vocabulary You must know the definitions of these terms 1. Synaptic Cleft 2. Neuron 3. Impulse 4. Sensory Neuron 5. Motor Neuron 6. Interneuron 7. Body (Soma) 8. Dendrite 9. Axon 10. Action Potential 11. Myelin Sheath (Myelin) 12. Afferent Neuron 13. Threshold 14. Neurotransmitter 15. Efferent Neurons 16. Axon Terminal 17. Stimulus 18. Refractory Period 19. Schwann 20. Nodes of Ranvier 21. Acetylcholine STEPS IN THE ACTION POTENTIAL 1. The presynaptic neuron sends neurotransmitters to postsynaptic neuron. 2. Neurotransmitters bind to receptors on the postsynaptic cell. - This action will either excite or inhibit the postsynaptic cell. - The soma becomes more positive. 3. The positive charge reaches the axon hillock. - Once the threshold of excitation is reached the neuron will fire an action potential. 4. Na+ channels open and Na+ is forced into the cell by the concentration gradient and the electrical gradient. - The neuron begins to depolarize. 5. The K+ channels open and K+ is forced out of the cell by the concentration gradient and the electrical gradient. - The neuron is depolarized. 6. The Na+ channels close at the peak of the action potential. - The neuron starts to repolarize. 7. The K+ channels close, but they close slowly and K+ leaks out. 8. The terminal buttons release neurotransmitter to the postsynaptic neuron. 9. The resting potential is overshot and the neuron falls to a -90mV (hyperpolarizes). - The neuron continues to repolarize. 10. The neuron returns to resting potential. The Synapse Label the following terms: Pre-synaptic membrane Neurotransmitters Post-synaptic membrane Synaptic cleft Vesicle Post-synaptic receptors .
    [Show full text]
  • Cell Biology and Fundamentals in Histology - En-Cours-2018-Liepr1004 Liepr1004 Cell Biology and Fundamentals in 2018 Histology
    Université catholique de Louvain - Cell biology and fundamentals in histology - en-cours-2018-liepr1004 liepr1004 Cell biology and fundamentals in 2018 histology 5 credits 45.0 h Q2 Teacher(s) Behets Wydemans Catherine ;Henriet Patrick ; Language : French Place of the course Louvain-la-Neuve Main themes The major themes are : - Characteristics common to all living species - The human cell, its functioning and division - Classical, evolutive and molecular genetics - Cellular bases in sexual reproduction - The differents cell types and their organisation in tissues - The major steps in human embryonic development Aims By the end of the module, students should understand the bases of unicity and diversity in the living world. They will know the structure and functioning of human cell and genome as well as the mechanisms of 1 cell division and embryonic development. Moreover, they will know the structure of the major types of human tissues. - - - - The contribution of this Teaching Unit to the development and command of the skills and learning outcomes of the programme(s) can be accessed at the end of this sheet, in the section entitled “Programmes/courses offering this Teaching Unit”. Content (auteurs - titulaires actuels) : P. Henriet and Ph. van den Bosch de Aguilar 1. UNICITY IN THE LIVING WORLD 2. THE HUMAN CELL 3. DIVERSITY IN THE LIVING WORLD 4. MOLECULAR GENETICS 5. CELL DIVISION 6. GAMETOGENESIS AND FERTILIZATION 7. INTRODUCTION TO HUMAN EMBRYOLOGY Histology 1. EPITHELIAL TISSUE 2. CONNECTIVE TISSUE 3. BLOOD TISSUE 4. MUSCLE TISSUE
    [Show full text]
  • Matthias Jacob Schleiden (1804–1881) [1]
    Published on The Embryo Project Encyclopedia (https://embryo.asu.edu) Matthias Jacob Schleiden (1804–1881) [1] By: Parker, Sara Keywords: cells [2] Matthias Jacob Schleiden helped develop the cell theory in Germany during the nineteenth century. Schleiden studied cells as the common element among all plants and animals. Schleiden contributed to the field of embryology [3] through his introduction of the Zeiss [4] microscope [5] lens and via his work with cells and cell theory as an organizing principle of biology. Schleiden was born in Hamburg, Germany, on 5 April 1804. His father was the municipal physician of Hamburg. Schleiden pursued legal studies at the University of Heidelberg [6] in Heidelberg, Germany, and he graduated in 1827. He established a legal practice in Hamburg, but after a period of emotional depression and an attempted suicide, he changed professions. He studied natural science at the University of Göttingen in Göttingen, Germany, but transferred to the University of Berlin [7] in Berlin, Germany, in 1835 to study plants. Johann Horkel, Schleiden's uncle, encouraged him to study plant embryology [3]. In Berlin, Schleiden worked in the laboratory of zoologistJ ohannes Müller [8], where he met Theodor Schwann. Both Schleiden and Schwann studied cell theory and phytogenesis, the origin and developmental history of plants. They aimed to find a unit of organisms common to the animal and plant kingdoms. They began a collaboration, and later scientists often called Schleiden and Schwann the founders of cell theory. In 1838, Schleiden published "Beiträge zur Phytogenesis" (Contributions to Our Knowledge of Phytogenesis). The article outlined his theories of the roles cells played as plants developed.
    [Show full text]
  • Crayfish Escape Behavior and Central Synapses
    Crayfish Escape Behavior and Central Synapses. III. Electrical Junctions and Dendrite Spikes in Fast Flexor Motoneurons ROBERT S. ZUCKER Department of Biological Sciences and Program in the Neurological Sciences, Stanford University, Stanford, California 94305 THE LATERAL giant fiber is the decision fiber and fast flexor motoneurons are located in for a behavioral response in crayfish in- the dorsal neuropil of each abdominal gan- volving rapid tail flexion in response to glion. Dye injections and anatomical recon- abdominal tactile stimulation (27). Each structions of ‘identified motoneurons reveal lateral giant impulse is followed by a rapid that only those motoneurons which have tail flexion or tail flip, and when the giant dentritic branches in contact with a giant fiber does not fire in response to such stim- fiber are activated by that giant fiber (12, uli, the movement does not occur. 21). All of tl ie fast flexor motoneurons are The afferent limb of the reflex exciting excited by the ipsilateral giant; all but F4, the lateral giant has been described (28), F5 and F7 are also excited by the contra- and the habituation of the behavior has latkral giant (21 a). been explained in terms of the properties The excitation of these motoneurons, of this part of the neural circuit (29). seen as depolarizing potentials in their The properties of the neuromuscular somata, does not always reach threshold for junctions between the fast flexor motoneu- generating a spike which propagates out the rons and the phasic flexor muscles have also axon to the periphery (14). Indeed, only t,he been described (13).
    [Show full text]
  • Catholic Christian Christian
    Religious Scientists (From the Vatican Observatory Website) https://www.vofoundation.org/faith-and-science/religious-scientists/ Many scientists are religious people—men and women of faith—believers in God. This section features some of the religious scientists who appear in different entries on these Faith and Science pages. Some of these scientists are well-known, others less so. Many are Catholic, many are not. Most are Christian, but some are not. Some of these scientists of faith have lived saintly lives. Many scientists who are faith-full tend to describe science as an effort to understand the works of God and thus to grow closer to God. Quite a few describe their work in science almost as a duty they have to seek to improve the lives of their fellow human beings through greater understanding of the world around them. But the people featured here are featured because they are scientists, not because they are saints (even when they are, in fact, saints). Scientists tend to be creative, independent-minded and confident of their ideas. We also maintain a longer listing of scientists of faith who may or may not be discussed on these Faith and Science pages—click here for that listing. Agnesi, Maria Gaetana (1718-1799) Catholic Christian A child prodigy who obtained education and acclaim for her abilities in math and physics, as well as support from Pope Benedict XIV, Agnesi would write an early calculus textbook. She later abandoned her work in mathematics and physics and chose a life of service to those in need. Click here for Vatican Observatory Faith and Science entries about Maria Gaetana Agnesi.
    [Show full text]
  • Plp-Positive Progenitor Cells Give Rise to Bergmann Glia in the Cerebellum
    Citation: Cell Death and Disease (2013) 4, e546; doi:10.1038/cddis.2013.74 OPEN & 2013 Macmillan Publishers Limited All rights reserved 2041-4889/13 www.nature.com/cddis Olig2/Plp-positive progenitor cells give rise to Bergmann glia in the cerebellum S-H Chung1, F Guo2, P Jiang1, DE Pleasure2,3 and W Deng*,1,3,4 NG2 (nerve/glial antigen2)-expressing cells represent the largest population of postnatal progenitors in the central nervous system and have been classified as oligodendroglial progenitor cells, but the fate and function of these cells remain incompletely characterized. Previous studies have focused on characterizing these progenitors in the postnatal and adult subventricular zone and on analyzing the cellular and physiological properties of these cells in white and gray matter regions in the forebrain. In the present study, we examine the types of neural progeny generated by NG2 progenitors in the cerebellum by employing genetic fate mapping techniques using inducible Cre–Lox systems in vivo with two different mouse lines, the Plp-Cre-ERT2/Rosa26-EYFP and Olig2-Cre-ERT2/Rosa26-EYFP double-transgenic mice. Our data indicate that Olig2/Plp-positive NG2 cells display multipotential properties, primarily give rise to oligodendroglia but, surprisingly, also generate Bergmann glia, which are specialized glial cells in the cerebellum. The NG2 þ cells also give rise to astrocytes, but not neurons. In addition, we show that glutamate signaling is involved in distinct NG2 þ cell-fate/differentiation pathways and plays a role in the normal development of Bergmann glia. We also show an increase of cerebellar oligodendroglial lineage cells in response to hypoxic–ischemic injury, but the ability of NG2 þ cells to give rise to Bergmann glia and astrocytes remains unchanged.
    [Show full text]
  • Immune Response and Histology of Humoral Rejection in Kidney
    Document downloaded from http://www.elsevier.es, day 23/05/2017. This copy is for personal use. Any transmission of this document by any media or format is strictly prohibited. n e f r o l o g i a 2 0 1 6;3 6(4):354–367 Revista de la Sociedad Española de Nefrología www.revistanefrologia.com Review Immune response and histology of humoral rejection in kidney transplantation a,∗ a b a Miguel González-Molina , Pedro Ruiz-Esteban , Abelardo Caballero , Dolores Burgos , a c a a Mercedes Cabello , Miriam Leon , Laura Fuentes , Domingo Hernandez a Nephrology Department, Regional University Hospital of Malaga, Malaga University, IBIMA, REDINREN RD12/0021/0015, Malaga, Spain b Immunology Department, Regional University Hospital of Malaga, Malaga University, IBIMA, REDINREN RD12/0021/0015, Malaga, Spain c Pathology Department, Regional University Hospital of Malaga, Malaga University, IBIMA, REDINREN RD12/0021/0015, Malaga, Spain a r t i c l e i n f o a b s t r a c t Article history: The adaptive immune response forms the basis of allograft rejection. Its weapons are direct Received 4 June 2015 cellular cytotoxicity, identified from the beginning of organ transplantation, and/or anti- Accepted 26 March 2016 bodies, limited to hyperacute rejection by preformed antibodies and not as an allogenic Available online 3 June 2016 response. This resulted in allogenic response being thought for decades to have just a cellu- lar origin. But the experimental studies by Gorer demonstrating tissue damage in allografts Keywords: due to antibodies secreted by B lymphocytes activated against polymorphic molecules were Immune response disregarded.
    [Show full text]
  • Oligodendrocytes in Development, Myelin Generation and Beyond
    cells Review Oligodendrocytes in Development, Myelin Generation and Beyond Sarah Kuhn y, Laura Gritti y, Daniel Crooks and Yvonne Dombrowski * Wellcome-Wolfson Institute for Experimental Medicine, Queen’s University Belfast, Belfast BT9 7BL, UK; [email protected] (S.K.); [email protected] (L.G.); [email protected] (D.C.) * Correspondence: [email protected]; Tel.: +0044-28-9097-6127 These authors contributed equally. y Received: 15 October 2019; Accepted: 7 November 2019; Published: 12 November 2019 Abstract: Oligodendrocytes are the myelinating cells of the central nervous system (CNS) that are generated from oligodendrocyte progenitor cells (OPC). OPC are distributed throughout the CNS and represent a pool of migratory and proliferative adult progenitor cells that can differentiate into oligodendrocytes. The central function of oligodendrocytes is to generate myelin, which is an extended membrane from the cell that wraps tightly around axons. Due to this energy consuming process and the associated high metabolic turnover oligodendrocytes are vulnerable to cytotoxic and excitotoxic factors. Oligodendrocyte pathology is therefore evident in a range of disorders including multiple sclerosis, schizophrenia and Alzheimer’s disease. Deceased oligodendrocytes can be replenished from the adult OPC pool and lost myelin can be regenerated during remyelination, which can prevent axonal degeneration and can restore function. Cell population studies have recently identified novel immunomodulatory functions of oligodendrocytes, the implications of which, e.g., for diseases with primary oligodendrocyte pathology, are not yet clear. Here, we review the journey of oligodendrocytes from the embryonic stage to their role in homeostasis and their fate in disease. We will also discuss the most common models used to study oligodendrocytes and describe newly discovered functions of oligodendrocytes.
    [Show full text]
  • Chapter 8 Nervous System
    Chapter 8 Nervous System I. Functions A. Sensory Input – stimuli interpreted as touch, taste, temperature, smell, sound, blood pressure, and body position. B. Integration – CNS processes sensory input and initiates responses categorizing into immediate response, memory, or ignore C. Homeostasis – maintains through sensory input and integration by stimulating or inhibiting other systems D. Mental Activity – consciousness, memory, thinking E. Control of Muscles & Glands – controls skeletal muscle and helps control/regulate smooth muscle, cardiac muscle, and glands II. Divisions of the Nervous system – 2 anatomical/main divisions A. CNS (Central Nervous System) – consists of the brain and spinal cord B. PNS (Peripheral Nervous System) – consists of ganglia and nerves outside the brain and spinal cord – has 2 subdivisions 1. Sensory Division (Afferent) – conducts action potentials from PNS toward the CNS (by way of the sensory neurons) for evaluation 2. Motor Division (Efferent) – conducts action potentials from CNS toward the PNS (by way of the motor neurons) creating a response from an effector organ – has 2 subdivisions a. Somatic Motor System – controls skeletal muscle only b. Autonomic System – controls/effects smooth muscle, cardiac muscle, and glands – 2 branches • Sympathetic – accelerator “fight or flight” • Parasympathetic – brake “resting and digesting” * 4 Types of Effector Organs: skeletal muscle, smooth muscle, cardiac muscle, and glands. III. Cells of the Nervous System A. Neurons – receive stimuli and transmit action potentials
    [Show full text]
  • Satellitosis, a Crosstalk Between Neurons, Vascular Structures and Neoplastic Cells in Brain Tumours; Early Manifestation of Invasive Behaviour
    cancers Review Satellitosis, a Crosstalk between Neurons, Vascular Structures and Neoplastic Cells in Brain Tumours; Early Manifestation of Invasive Behaviour Prospero Civita 1,2,* , Ortenzi Valerio 3 , Antonio Giuseppe Naccarato 3 , Mark Gumbleton 2 and Geoffrey J. Pilkington 1,2,4,* 1 Brain Tumour Research Centre, Institute of Biological and Biomedical Sciences (IBBS), School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DT, UK 2 School of Pharmacy and Pharmaceutical Sciences, College of Biomedical and Life Sciences, Cardiff University, Cardiff CF10 3NB, UK; gumbleton@cardiff.ac.uk 3 Department of Translational Research and New Technologies in Medicine and Surgery, Pisa University Hospital, 56100 Pisa, Italy; [email protected] (O.V.); [email protected] (A.G.N.) 4 Division of Neuroscience, Department of Basic and Clinical Neuroscience, Institute of Psychiatry & Neurology, King’s College London, London SE5 9RX, UK * Correspondence: CivitaP@cardiff.ac.uk (P.C.); geoff[email protected] (G.J.P.) Received: 9 November 2020; Accepted: 4 December 2020; Published: 11 December 2020 Simple Summary: This article reviews the concept of cellular satellitosis as originally described histologically by Santiago Ramón y Cajal in 1899 and Hans Joachim Scherer, more specifically in the context of glioblastoma invasiveness, during the early part of the 20th century. With the advent of new and emerging molecular technologies in the 21st century, the significance of both vascular and neuronal satellitosis by neoplastic cells offers intriguing possibilities into further clarifying the development, pathobiology and therapy of malignant glioma through closer investigation into the nature of these histological hallmarks.
    [Show full text]
  • Neuron Morphology Influences Axon Initial Segment Plasticity1,2,3
    New Research Neuronal Excitability Neuron Morphology Influences Axon Initial Segment Plasticity1,2,3 Allan T. Gulledge1 and Jaime J. Bravo2 DOI:http://dx.doi.org/10.1523/ENEURO.0085-15.2016 1Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03756, and 2Thayer School of Engineering at Dartmouth, Hanover, New Hampshire 03755 Visual Abstract In most vertebrate neurons, action potentials are initiated in the axon initial segment (AIS), a specialized region of the axon containing a high density of voltage-gated sodium and potassium channels. It has recently been proposed that neurons use plasticity of AIS length and/or location to regulate their intrinsic excitability. Here we quantify the impact of neuron morphology on AIS plasticity using computational models of simplified and realistic somatodendritic morphologies. In small neurons (e.g., den- tate granule neurons), excitability was highest when the AIS was of intermediate length and located adjacent to the soma. Conversely, neu- rons having larger dendritic trees (e.g., pyramidal neurons) were most excitable when the AIS was longer and/or located away from the soma. For any given somatodendritic morphology, increasing dendritic mem- brane capacitance and/or conductance favored a longer and more distally located AIS. Overall, changes to AIS length, with corresponding changes in total sodium conductance, were far more effective in regulating neuron excitability than were changes in AIS location, while dendritic capacitance had a larger impact on AIS performance than did dendritic conductance. The somatodendritic influence on AIS performance reflects modest soma- to-AIS voltage attenuation combined with neuron size-dependent changes in AIS input resistance, effective membrane time constant, and isolation from somatodendritic capacitance.
    [Show full text]
  • How Does an Axon Grow?
    Downloaded from genesdev.cshlp.org on October 2, 2021 - Published by Cold Spring Harbor Laboratory Press REVIEW How does an axon grow? Jeffrey L. Goldberg1 Department of Neurobiology, Stanford University School of Medicine, Stanford, California 94305, USA How do axons grow during development, and why do cisions to advance, retract, pause, or turn (Fig. 1). All of they fail to regrow when injured? In the complicated these are potential regulatory sites that could control a mesh of our nervous system, the axon is the information neuron’s ability to elongate or regenerate its axon. superhighway, carrying all of the data we use to sense our environment and carry out behaviors. To wire up our Production of the building blocks, nervous system properly, neurons must elongate their both membrane and cytoplasmic axons during development to reach their targets. This is no simple task, however. The complex morphology of Rapid axon growth requires rapid manufacture and sup- axons and dendrites puts neurons among the most intri- ply of cytoplasm and membrane. Where are the lipid and cate and beautiful cells in the body. Knowledge of how protein building blocks made? It was known from classic neurons extend axons and dendrites, elongate at a par- experiments that axons cut off from the cell bodies of ticular rate, and stop growing at the proper time is criti- adult sensory neurons continue to elongate in culture cal to understanding the development of our nervous (Shaw and Bray 1977), but evidence for local production system, yet the regulation of these processes is poorly of membrane and cytoplasmic elements went lacking for understood.
    [Show full text]