DOCSLIB.ORG

Development and Anatomical Organization of the Nervous System I Contents

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Development and Anatomical Organization of the Nervous System I Contents Development and anatomical organization of the nervous system I Contents: 1. Functional organization of the nervous system 2. Development of nervous systems 2.1 Cnidarians: polyps and medusae (Hydra) 2.2 Flatworms and roundworms (C. elegans) 2.3 Molluscs (Aplysia and Octopus) 2.4 Arthropodes (Drosophila) 3. Pattern formation in Drosophila Literature: Kandel ER, Schwartz JH, Jessell TM. Principles of neural science. New York: McGraw-Hill *** Kahle, W. Taschenatlas der Anatomie. Band 3: Nervensystem und Sinnesorgane. Stuttgart: Thieme *** Functional organization of the nervous system Information processing (integration) Sensory Input (receptors) Motor Output (muscles) Somatic part of the PNS (Campbell et al., Biologie) Development of nervous systems Cnidarians („Nesseltiere“): polyps and medusae - „Lowest“ organism with a neuronal network Polyps: Sessile form of the Cnidarian building plan Hydra Medusae (yellyfish): free-floating form of the Cnidarian building plan Aurelia aurita Aurelia aurita („Ohrenqualle“) Hydra Development of nervous systems Nervous system of Cnidarians Distributed nerve net (no central nervous system) as the sole nervous system (similar to the autonomous nerve system at higher organisms) Sensory Motor Integration Input Output (Interneurons) (receptors) (muscles) • mechanical, chemical and electrical signals • changes in light and temperature Development of nervous systems Nervous system of Cnidarians Hydra - Most simple nervous system: Hydra → Model system - Reaction to mechanical, chemical (e.g. glutathione) and electrical stimuli as well as changes in light and temperature - Peptide neurotransmitters (no low molecular weight transmitters) >12 neuropeptides with transmitter function Hydra - No glial cells, no myelinization - Symmetrical synapses (no distinction between axons and dendrites) Development of nervous systems Nervous system of Cnidarians Medusae - Begin of a functional differentiation Aurelia aurita („Ohrenqualle“) net of multipolar nerve cells below the epithelial cell layer in connection to sensory cells („exumbrellar nerve ring“): sensory function net of nerve cells on top of muscle cells („subumbrellar nerve ring“) with electrical coupling: motor coordination Development of nervous systems Nervous system of flatworms and roundworms „Lowest“ organisms with a central nervous system - Contain a body axis - Contain a spezialized head region („cephalization“) - Contain an accumulation of nerve cells in the head region (nerve ring, „brain“) Important model organism: Caenorhabditis elegans (roundworm, nematode) Development of nervous systems Nervous system of flatworms and roundworms Formation of a medullary strand (“Markstrang”) in the ventral cord: - forms transition between diffuse and centralized nervous system: nerve cells arrange themselves into strand-like associations, but the cell bodies are not yet exclusively limited to ganglia Development of nervous systems Nervous system of flatworms and roundworms C. elegans as model organism to study the development of the nervous system - Complete sequence information (1998) - 302 nerve cells with defined origin (about 1000 cells in total) - Complete electron microscopic reconstruction of the nervous system (Brenner and co-workers) Sydney Brenner † 5.4.2019 Nobel prize, 2002 Development of nervous systems Nervous system of molluscs High complexity: Spectrum from relatively simple central nervous systems (similar to C. elegans) to the most developed nervous systems of the evertebrates (cephalopods, e.g. octopus) Model organism with a relatively simple central nervous system: Marine snail Aplysia californica with about 20,000 CNS neurons Development of nervous systems Nervous system of molluscs Aplysia: Nervous system is organized in separate ganglia Model organism for analysis of cellular mechanisms of simple forms of implicit learning (gill retraction reflex): - Habituation - Sensitization - classic conditioning Development of nervous systems Nervous system of molluscs Aplysia: Model organism for analysis of cellular mechanisms of simple forms of implicit learning Classic conditioning: conditioned stimulus: tactile stimulus of the siphon unconditioned stimulus: electrical shock at the tail Development of nervous systems Nervous system of molluscs Aplysia: Model organism for analysis of cellular mechanisms of simple forms of implicit learning Classic conditioning: conditioned stimulus: tactile stimulus of the siphon unconditioned stimulus: electrical shock at the tail Development of nervous systems Nervous system of molluscs Aplysia: Model organism for analysis of cellular mechanisms of simple forms of implicit learning Operant conditioning (an originally insignificant spontaneous behavior can be preferred / avoided by reinforcement or punishment) in Aplysia Hawkins, R.D., Clark, G.A., Kandel, E.R. (2006) Operant conditioning of gill withdrawal in Aplysia“, J. Neurosci. 26:2443-2448 Aplysia was taught to keep his gills contracted to avoid electrical shock Development of nervous systems Nervous system of molluscs Octopus: - Highly developed nervous system (around 42 million nerve cells in the brain) - Good learning ability - Complex behavior is highly visually controlled - Peripheral and central nervous ganglia - Central nervous ganglia are called lobes (> 30), which together form the brain and are enclosed by a cartilage capsule Chemotactile and visual centers are largely separated and each consist of four lobes (topical organization) Development of nervous systems Nervous system of arthropodes Subdivision of the arthropods in - Chelicerata (spider-like) - Crustacea (crayfish) - Tracheata (millipedes and insects) Insects (Insecta) are the experimentally most important and species-rich group CNS consists of dorsal brain (fused cerebral ganglia) and ventral nerve cord Development of nervous systems Nervous system of arthropodes Brain: Complex fine structure consisting of cell body regions (nuclei), fiber bundle areas (nerve tracts), multiple neuropil centers (network of nerve fibers and glial cell processes) Brain is divided into three parts: protocerebrum, deutocerebrum, and tritocerebrum with functional spezialization Development of nervous systems Nervous system of arthropodes Protocerebrum: two hemispheres that merge laterally into the optical lobes, contains central body (probably motor control) and paired mushroom bodies (multimodal integration center for coordination of olfactory and visual excitation) Development of nervous systems Nervous system of arthropodes Deutocerebrum: origin of the antenna nerves with a sensory and motor component olfactory and mechanosensory receptor neurons end in different areas of the Deutocerebrum: → Topical organization Tritocerebrum: innervation of the head surface, origin of the frontal connective Development of nervous systems Nervous system of arthropodes ventral nerve cord: - functional equivalent of the vertebrate spinal cord - consists of paired segmental ganglia running along the ventral midline of the thorax and abdomen like a “rope ladder” (“Strickleiter”) - contains efferent projecting motor neurons and afferent sensory fibers Development of nervous systems Nervous system of arthropodes Formation of the ganglion chain is a model system for axonal pathfinding: Pioneer neurons create the fiber tracts of the commissures (cross-connections) and connectives (longitudinal connections) Pattern formation in Drosophila Pattern formation: Regionalization of the nervous system Mechanisms of pattern formation: 1. Segmentation: Subdivision of the neural tube into axially repeated, module-like units (neuromeres) Basis: differential gene activity (segmentation genes) 2. Determination of the anatomical identity of the individual segments: Discovery of the so-called “homeotic genes” in Drosophila (in homologous form also in vertebrates) as regulatory genes Mutations in the homeotic genes lead to pattern formation anomalies Pattern formation in Drosophila Homeotic genes in vertebrates In vertebrates, homeotic “HOX genes” have a spatial expression pattern comparable to that in Drosophila Humans have 39 HOX genes, which are organized in 4 clusters and play an important role in the development of the CNS, skeleton, limbs and various internal organs Some limb malformations are due to mutations in the HOX genes (Goodman (2002) Limb malformations and the human HOX genes. Am. J. Med. Genet. 112:256-265).
Load more

Recommended publications
  • Convergent Evolution of the Ladder-Like Ventral Nerve Cord in Annelida Conrad Helm1*, Patrick Beckers2, Thomas Bartolomaeus2, Stephan H
    Helm et al. Frontiers in Zoology (2018) 15:36 https://doi.org/10.1186/s12983-018-0280-y RESEARCH Open Access Convergent evolution of the ladder-like ventral nerve cord in Annelida Conrad Helm1*, Patrick Beckers2, Thomas Bartolomaeus2, Stephan H. Drukewitz3, Ioannis Kourtesis1, Anne Weigert4, Günter Purschke5, Katrine Worsaae6, Torsten H. Struck7 and Christoph Bleidorn1,8* Abstract Background: A median, segmented, annelid nerve cord has repeatedly been compared to the arthropod and vertebrate nerve cords and became the most used textbook representation of the annelid nervous system. Recent phylogenomic analyses, however, challenge the hypothesis that a subepidermal rope-ladder-like ventral nerve cord (VNC) composed of a paired serial chain of ganglia and somata-free connectives represents either a plesiomorphic or a typical condition in annelids. Results: Using a comparative approach by combining phylogenomic analyses with morphological methods (immunohistochemistry and CLSM, histology and TEM), we compiled a comprehensive dataset to reconstruct the evolution of the annelid VNC. Our phylogenomic analyses generally support previous topologies. However, the so far hard-to-place Apistobranchidae and Psammodrilidae are now incorporated among the basally branching annelids with high support. Based on this topology we reconstruct an intraepidermal VNC as the ancestral state in Annelida. Thus, a subepidermal ladder-like nerve cord clearly represents a derived condition. Conclusions: Based on the presented data, a ladder-like appearance of the ventral nerve cord evolved repeatedly, and independently of the transition from an intraepidermal to a subepidermal cord during annelid evolution. Our investigations thereby propose an alternative set of neuroanatomical characteristics for the last common ancestor of Annelida or perhaps even Spiralia.
    [Show full text]
  • Animal Phylum Poster Porifera
    Phylum PORIFERA CNIDARIA PLATYHELMINTHES ANNELIDA MOLLUSCA ECHINODERMATA ARTHROPODA CHORDATA Hexactinellida -- glass (siliceous) Anthozoa -- corals and sea Turbellaria -- free-living or symbiotic Polychaetes -- segmented Gastopods -- snails and slugs Asteroidea -- starfish Trilobitomorpha -- tribolites (extinct) Urochordata -- tunicates Groups sponges anemones flatworms (Dugusia) bristleworms Bivalves -- clams, scallops, mussels Echinoidea -- sea urchins, sand Chelicerata Cephalochordata -- lancelets (organisms studied in detail in Demospongia -- spongin or Hydrazoa -- hydras, some corals Trematoda -- flukes (parasitic) Oligochaetes -- earthworms (Lumbricus) Cephalopods -- squid, octopus, dollars Arachnida -- spiders, scorpions Mixini -- hagfish siliceous sponges Xiphosura -- horseshoe crabs Bio1AL are underlined) Cubozoa -- box jellyfish, sea wasps Cestoda -- tapeworms (parasitic) Hirudinea -- leeches nautilus Holothuroidea -- sea cucumbers Petromyzontida -- lamprey Mandibulata Calcarea -- calcareous sponges Scyphozoa -- jellyfish, sea nettles Monogenea -- parasitic flatworms Polyplacophora -- chitons Ophiuroidea -- brittle stars Chondrichtyes -- sharks, skates Crustacea -- crustaceans (shrimp, crayfish Scleropongiae -- coralline or Crinoidea -- sea lily, feather stars Actinipterygia -- ray-finned fish tropical reef sponges Hexapoda -- insects (cockroach, fruit fly) Sarcopterygia -- lobed-finned fish Myriapoda Amphibia (frog, newt) Chilopoda -- centipedes Diplopoda -- millipedes Reptilia (snake, turtle) Aves (chicken, hummingbird) Mammalia
    [Show full text]
  • The Nervous System in Lumbriculus Variegatus C
    [ NOTE: The following is an unpublished summary about nervous system design and function in the blackworm, Lumbriculus variegatus (Class Oligochaeta). This worm is being used at high school and college levels for student laboratory exercises and research projects. It has proven quite useful and reliable for studies of segment regeneration, circulatory physiology, locomotion, eco-toxicology, and neurobiology (Drewes, 1996a; Lesiuk and Drewes, 1998; Drewes and Cain, 1998). The following article provides students and instructors with general information about this worm’s nervous system which is not currently available in any biology texts. Correspondence or questions about this information are welcome. Please address to: Charles Drewes, Zoology & Genetics, Room 339 Science II Building, Iowa State University, Ames, IA, 50011; or phone: (515) 294-8061; or email: [email protected] ]. ------------------------------------------------------------------------------------------------------------- Functional organization of the nervous system in Lumbriculus variegatus C. Drewes (April. 2002) The gross anatomy of the nervous system in Lumbriculus variegatus was originally described more than 70 years ago by Isossimow (1926), with an English summary of that work given in Stephenson’s book, The Oligochaeta (1930). Virtually no published studies of this worm’s neurophysiology or behavior were done until the late 1980’s. The central nervous system in Lumbriculus consists of a cerebral ganglion (or “brain”), located in segment #1, and a ventral nerve cord that extends through every body segment (Figure 1). In each segment, except the first two, the ventral nerve cord gives rise to four pairs of segmental nerves. [Comparative note: In the earthworm, Lumbricus terrestris, there are three pairs of segmental nerve in each segment.] The segmental nerves extend laterally into the body wall where they form a series of parallel rings that extend within and around the body wall (for review, see Stephenson, 1930.).
    [Show full text]
  • Study on the Efferent Innervation of the Body Wall Musculature of Lumbricus Terrestris (L)
    Loyola University Chicago Loyola eCommons Master's Theses Theses and Dissertations 1975 Study on the Efferent Innervation of the Body Wall Musculature of Lumbricus Terrestris (L) Carol A. Aslam Loyola University Chicago Follow this and additional works at: https://ecommons.luc.edu/luc_theses Part of the Anatomy Commons Recommended Citation Aslam, Carol A., "Study on the Efferent Innervation of the Body Wall Musculature of Lumbricus Terrestris (L)" (1975). Master's Theses. 2749. https://ecommons.luc.edu/luc_theses/2749 This Thesis is brought to you for free and open access by the Theses and Dissertations at Loyola eCommons. It has been accepted for inclusion in Master's Theses by an authorized administrator of Loyola eCommons. For more information, please contact [email protected]. This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License. Copyright © 1975 Carol A. Aslam STUDY ON THE EFFERENT INNERVATION OF THE BODY WALL ~USCULATURE OF LUMBRICUS TERRESTRIS (L.) by Carol Aslam A Thesis Submitted to the Faculty of the Graduate School of Loyola University of Chicago in Partial Fulfillment of the Requirements for the Degree of Master of Science November 1975 .s. ' '.. ACKNOWLEDGMENTS The author will always be indebted to her advisor, Dr. Robert Hadek, for unfailing support and scientific criticism throughout the preparation of this manuscript. Special thanks are also due to members of the De­ partment of Anatomy who generously gave of their time, counsel and technical assistance. The encouragement of my husband and enduring patience of my children have made possible the completion of this program. ii BIOGkAPllY Carol A.
    [Show full text]
  • The Ventral Nerve Cord of Lithobius Forficatus (Lithobiomorpha): Morphology, Neuroanatomy, and Individually Identifiable Neurons
    76 (3): 377 – 394 11.12.2018 © Senckenberg Gesellschaft für Naturforschung, 2018. A comparative analysis of the ventral nerve cord of Lithobius forficatus (Lithobiomorpha): morphology, neuroanatomy, and individually identifiable neurons Vanessa Schendel, Matthes Kenning & Andy Sombke* University of Greifswald, Zoological Institute and Museum, Cytology and Evolutionary Biology, Soldmannstrasse 23, 17487 Greifswald, Germany; Vanessa Schendel [[email protected]]; Matthes Kenning [[email protected]]; Andy Sombke * [andy. [email protected]] — * Corresponding author Accepted 19.iv.2018. Published online at www.senckenberg.de/arthropod-systematics on 27.xi.2018. Editors in charge: Markus Koch & Klaus-Dieter Klass Abstract. In light of competing hypotheses on arthropod phylogeny, independent data are needed in addition to traditional morphology and modern molecular approaches. One promising approach involves comparisons of structure and development of the nervous system. In addition to arthropod brain and ventral nerve cord morphology and anatomy, individually identifiable neurons (IINs) provide new charac- ter sets for comparative neurophylogenetic analyses. However, very few species and transmitter systems have been investigated, and still fewer species of centipedes have been included in such analyses. In a multi-methodological approach, we analyze the ventral nerve cord of the centipede Lithobius forficatus using classical histology, X-ray micro-computed tomography and immunohistochemical experiments, combined with confocal laser-scanning microscopy to characterize walking leg ganglia and identify IINs using various neurotransmitters. In addition to the subesophageal ganglion, the ventral nerve cord of L. forficatus is composed of the forcipular ganglion, 15 well-separated walking leg ganglia, each associated with eight pairs of nerves, and the fused terminal ganglion. Within the medially fused hemiganglia, distinct neuropilar condensations are located in the ventral-most domain.
    [Show full text]
  • Larval Nervous Systems
    © 2015. Published by The Company of Biologists Ltd | The Journal of Experimental Biology (2015) 218, 629-636 doi:10.1242/jeb.109603 REVIEW Larval nervous systems: true larval and precocious adult Claus Nielsen* ABSTRACT be specialized into rows of ganglia connected by connectives] and the The apical organ of ciliated larvae of cnidarians and bilaterians is a Chordonia by an unpaired dorsal neural tube. The division of the true larval organ that disappears before or at metamorphosis. It Bilateria into Protostomia and Deuterostomia (=Cordonia + appears to be sensory, probably involved in metamorphosis, but Ambulacraria) (Grobben, 1908) is still universally accepted and is knowledge is scant. The ciliated protostome larvae show now supported by numerous phylogenomic studies (Hejnol et al., ganglia/nerve cords that are retained as the adult central nervous 2009; Wheeler et al., 2009; Edgecombe et al., 2011). However, the system (CNS). Two structures can be recognized, viz. a pair of interpretation of the dorsal/ventral orientation of the two groups has cerebral ganglia, which form the major part of the adult brain, and a been challenged, and it now appears that the two longitudinal nerve blastoporal (circumblastoporal) nerve cord, which becomes cords are homologous (see below). differentiated into a perioral loop, paired or secondarily fused ventral The topology of the bilaterian part of the animal tree of life is nerve cords and a small perianal loop. The anterior loop becomes relatively well established, but there is not agreement about the part of the brain. This has been well documented through cell-lineage inter-relationships of the basal metazoan groups.
    [Show full text]
  • Imaging Neural Activity in the Ventral Nerve Cord of Behaving Adult
    bioRxiv preprint doi: https://doi.org/10.1101/250118; this version posted January 22, 2018. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. Imaging neural activity in the ventral nerve cord of behaving adult Drosophila Chin-Lin Chen1,2,*, Laura Hermans1,2,*, Meera C. Viswanathan3,4, Denis Fortun5,6, Michael Unser5, Anthony Cammarato3,4, Michael H. Dickinson7, Pavan Ramdya1,2,‡ Affiliations: 1 Brain Mind Institute, École Polytechnique Fédérale de Lausanne, Lausanne, CH-1015, Switzerland 2 Interfaculty Institute of Bioengineering, École Polytechnique Fédérale de Lausanne, Lausanne, CH-1015, Switzerland 3 Department of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA 4 Department of Physiology, Johns Hopkins University, Baltimore, MD 21205, USA 5 Biomedical Imaging Group, École Polytechnique Fédérale de Lausanne, Lausanne, CH-1015, Switzerland 6 Signal Processing core of the Center for Biomedical Imaging (CIBM-SP), École Polytechnique Fédérale de Lausanne, Lausanne, CH-1015, Switzerland 7 Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA * These authors contributed equally ‡ Correspondence should be addressed to: [email protected] bioRxiv preprint doi: https://doi.org/10.1101/250118; this version posted January 22, 2018. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license.
    [Show full text]
  • Fuxianhuiid Ventral Nerve Cord and Early Nervous System Evolution in Panarthropoda
    Fuxianhuiid ventral nerve cord and early nervous system evolution in Panarthropoda Jie Yanga, Javier Ortega-Hernándezb,1, Nicholas J. Butterfieldb, Yu Liua,c,d, George S. Boyanc, Jin-bo Houa, Tian Lane, and Xi-guang Zhanga,2 aYunnan Key Laboratory for Paleobiology, Yunnan University, Kunming 650091, China; bDepartment of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, United Kingdom; cDevelopmental Neurobiology Group, Biocenter, Ludwig-Maximilians-Universität, 82152 Martinsried, Germany; dGeoBio-Center Ludwig-Maximilians-Universität, Munich 80333, Germany; and eCollege of Resources and Environmental Engineering, Guizhou University, Guiyang 550003, China Edited by Gregory D. Edgecombe, The Natural History Museum, London, United Kingdom, and accepted by the Editorial Board January 29, 2016 (received for review November 14, 2015) Panarthropods are typified by disparate grades of neurological feature as the VNC. This interpretation is supported by com- organization reflecting a complex evolutionary history. The fossil parisons with other preserved components of the internal anat- record offers a unique opportunity to reconstruct early character omy. For instance, the VNC can be readily distinguished from evolution of the nervous system via exceptional preservation in the digestive tract of C. kunmingensis, which is expressed as a extinct representatives. Here we describe the neurological archi- comparatively larger (maximum width, ∼860 μm) but fully tecture of the ventral nerve cord (VNC) in the upper-stem group compressed, linear structure running almost the entire length of euarthropod Chengjiangocaris kunmingensis from the early Cam- the animal (23, figure 1 d and e). The VNC extends from at least brian Xiaoshiba Lagerstätte (South China). The VNC of C. kunmin- the five anteriormost reduced trunk tergites (i.e., dorsal exo- gensis comprises a homonymous series of condensed ganglia that skeletal plates) to tergite T23 at the posterior end of the trunk extend throughout the body, each associated with a pair of bi- (Figs.
    [Show full text]
  • REVIEW the Neuroendocrine System of Invertebrates
    555 REVIEW The neuroendocrine system of invertebrates: a developmental and evolutionary perspective Volker Hartenstein Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, California 90095, USA (Requests for offprints should be addressed to V Hartenstein; Email: [email protected]) Abstract Neuroendocrine control mechanisms are observed in all the evolutionary origin and possible homologies between animals that possess a nervous system. Recent analyses of neuroendocrine systems. This review intends to provide a neuroendocrine functions in invertebrate model systems brief overview of invertebrate neuroendocrine systems and to reveal a great degree of similarity between phyla as far apart discuss aspects of their development that appear to be as nematodes, arthropods, and chordates. Developmental conserved between insects and vertebrates. studies that emphasize the comparison between different Journal of Endocrinology (2006) 190, 555–570 animal groups will help to shed light on questions regarding Endocrine and neuroendocrine cells through absorption and excretion, the formation and maturation of gametes, and growth and regeneration of the Cells in multicellular animals communicate through signaling body. In many instances, endocrine glands form an integrated mechanisms that take place at direct intercellular contacts, or system in which hormonal production and release is that involve signals released systemically into the extracellular controlled through feed back loops. space where they diffuse over large distances and are able to Most hormones found throughout the animal kingdom are affect targets far removed from the signaling source. The first short polypeptides, produced by proteolytic cleavage from mechanism, communication of cells that are in direct contact, larger precursor proteins, called prohormones.
    [Show full text]
  • Owenia Fusiformis – a Basally Branching Annelid Suitable For
    Helm et al. BMC Evolutionary Biology (2016) 16:129 DOI 10.1186/s12862-016-0690-4 RESEARCH ARTICLE Open Access Owenia fusiformis – a basally branching annelid suitable for studying ancestral features of annelid neural development Conrad Helm*, Oliver Vöcking, Ioannis Kourtesis and Harald Hausen Abstract Background: Comparative investigations on bilaterian neurogenesis shed light on conserved developmental mechanisms across taxa. With respect to annelids, most studies focus on taxa deeply nested within the annelid tree, while investigations on early branching groups are almost lacking. According to recent phylogenomic data on annelid evolution Oweniidae represent one of the basally branching annelid clades. Oweniids are thought to exhibit several plesiomorphic characters, but are scarcely studied - a fact that might be caused by the unique morphology and unusual metamorphosis of the mitraria larva, which seems to be hardly comparable to other annelid larva. In our study, we compare the development of oweniid neuroarchitecture with that of other annelids aimed to figure out whether oweniids may represent suitable study subjects to unravel ancestral patterns of annelid neural development. Our study provides the first data on nervous system development in basally branching annelids. Results: Based on histology, electron microscopy and immunohistochemical investigations we show that development and metamorphosis of the mitraria larva has many parallels to other annelids irrespective of the drastic changes in body shape during metamorphosis. Such significant changes ensuing metamorphosis are mainly from diminution of a huge larval blastocoel and not from major restructuring of body organization. The larval nervous system features a prominent apical organ formed by flask-shaped perikarya and circumesophageal connectives that interconnect the apical and trunk nervous systems, in addition to serially arranged clusters of perikarya showing 5-HT-LIR in the ventral nerve cord, and lateral nerves.
    [Show full text]
  • The Contribution of Invertebrates to the Understanding of the Vertebrate Nervous System, Its Mechanisms, Functions and Pathologi
    1 The contribution of invertebrates to the understanding of the vertebrate 2 nervous system, its mechanisms, functions and pathological dysfunctions. 3 Martin Giurfa 1) and Hans-Joachim Pflüger2) 4 Research Center on Animal Cognition, Center of Integrative Biology, CNRS - University Paul Sabatier - 5 Toulouse III, 118 Route de Narbonne, 31062 Toulouse cedex 9, FRANCE 1), and Institute of Biology, 6 Neurobiology; Freie Universitaet Berlin, Koenigin-Luise-Strasse 1-3, 14195 Berlin, GERMANY 2) 7 The human brain and the nervous system are the immediate result of several (6-7) million years of 8 hominid evolution, and ultimately of organismic evolution as they bear many similarities to the brain 9 and nervous system of vertebrates. We readily accept that all vertebrate organisms such as fish, 10 amphibians, reptiles, birds and mammals, share many anatomical features and major organs 11 corresponding to our human organism: they have guts and intestines; they possess a circulatory system 12 with a heart, kidneys and an excretory system. Less well accepted, perhaps, is the fact that these 13 animals have brains and nervous systems which are also related to us. Novel analyses of the nervous 14 systems of vertebrates allow retracing the occurring evolutionary changes with unprecedented 15 precision using new technical tools from molecular biology, immunocytochemistry or molecular 16 genetics. These analyses reveal the evolution of particular brain structures in new environments and 17 their relation to different life styles, something that biologists call an “ecological niche”. We readily 18 accept that primates like chimpanzees have many similarities in their body shape and behaviour to us, 19 namely because they resemble to ourselves in many aspects.
    [Show full text]
  • Is the Tubular Nervous System Related with the Development of Skeletal Muscle in Chordates? – Areview
    THIEME Review Article 207 Is the Tubular Nervous System Related with the Development of Skeletal Muscle in Chordates? – AReview Rajani Singh1 1 Department of Anatomy, All India Institute of Medical Sciences Address for correspondence Dr. Rajani Singh, Department of (AIIMS), Rishikesh, Uttrakhand, India Anatomy, All India Institute of Medical Sciences (AIIMS), Veerbhadra Marg Pashulok, Rishikesh, 249201, Rishikesh, Uttrakhand, India J Morphol Sci 2018;35:207–211. (e-mail: [email protected]). Abstract Many theories and arguments have been proposed regarding the ancestors of the vertebrates and the factors that lead to the evolution of the tubular nervous system. Invertebrates had simpler smooth muscles. Vertebrates acquired additional skeletal muscles. The skeletal muscles were found to be associated with a new type of tubular nervous system. There were three stages in the evolution of the nervous system. The most primitive was the network type, in which there was neither a polarization nor a centralization of neurons. The second stage was characterized by the evolution of a ganglionic nervous system. Then, the tubular type of nervous system appeared for the Keywords first time in chordates. Therefore, the author hypothesizes that the skeletal muscle ► nervous system developed simultaneously with the tubular nervous system. The chorda mesoderm ► skeletal muscle and, thereby, the skeletal muscle, induced the formation of a tubular nervous system in ► chordates chordates. In the present article, the author aims to analyze the nervous
    [Show full text]