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,