Biomaterial Database

Excessive numbers of axons after early enucleation and blockade of metamorphosis in the oculomotor nerve of Xenopus laevis. 1988

N Schönenberger, and G Escher

Institut d'Anatomie, Université de Lausanne, Switzerland.

The number of axons in the oculomotor (OM) nerve of Xenopus laevis tadpoles was counted in unoperated and in unilaterally enucleated animals, raised in 0.4 g/l thiourea (TU), a thyroid-blocking agent, which arrested their development at premetamorphosis. In unoperated animals the number of axons starts to decrease with metamorphosis. When raised in TU, the tadpoles do not metamorphose and show no axon loss; rather, there is a moderate increase in axon number (13%) after 6 months of thiourea-treatment. Thus metamorphosis is necessary for the initiation of axon loss. In unilaterally enucleated tadpoles, increased axon loss occurs at metamorphosis in the OM nerve of the operated side, but the contralateral OM nerve shows no loss at all. When these animals are treated with TU, there is, as compared with the effects of the TU-treatment in unoperated animals, an increase of 7% in the ipsilateral side and of 28% in the contralateral one. Thus thyroxine blockade prevents the effects of unilateral enucleation and induces an excessive number of axons during the period observed. We postulate that through blockade of metamorphosis, axon elimination is arrested, while their production continues, and that these effects are accentuated by manipulation of the axonal target.

UI	MeSH Term	Description	Entries
D008675	Metamorphosis, Biological	Profound physical changes during maturation of living organisms from the immature forms to the adult forms, such as from TADPOLES to frogs; caterpillars to BUTTERFLIES.	Biological Metamorphosis,Biological Metamorphoses,Metamorphoses, Biological
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D009186	Myelin Sheath	The lipid-rich sheath surrounding AXONS in both the CENTRAL NERVOUS SYSTEMS and PERIPHERAL NERVOUS SYSTEM. The myelin sheath is an electrical insulator and allows faster and more energetically efficient conduction of impulses. The sheath is formed by the cell membranes of glial cells (SCHWANN CELLS in the peripheral and OLIGODENDROGLIA in the central nervous system). Deterioration of the sheath in DEMYELINATING DISEASES is a serious clinical problem.	Myelin,Myelin Sheaths,Sheath, Myelin,Sheaths, Myelin
D009473	Neuronal Plasticity	The capacity of the NERVOUS SYSTEM to change its reactivity as the result of successive activations.	Brain Plasticity,Plasticity, Neuronal,Axon Pruning,Axonal Pruning,Dendrite Arborization,Dendrite Pruning,Dendritic Arborization,Dendritic Pruning,Dendritic Remodeling,Neural Plasticity,Neurite Pruning,Neuronal Arborization,Neuronal Network Remodeling,Neuronal Pruning,Neuronal Remodeling,Neuroplasticity,Synaptic Plasticity,Synaptic Pruning,Arborization, Dendrite,Arborization, Dendritic,Arborization, Neuronal,Arborizations, Dendrite,Arborizations, Dendritic,Arborizations, Neuronal,Axon Prunings,Axonal Prunings,Brain Plasticities,Dendrite Arborizations,Dendrite Prunings,Dendritic Arborizations,Dendritic Prunings,Dendritic Remodelings,Network Remodeling, Neuronal,Network Remodelings, Neuronal,Neural Plasticities,Neurite Prunings,Neuronal Arborizations,Neuronal Network Remodelings,Neuronal Plasticities,Neuronal Prunings,Neuronal Remodelings,Neuroplasticities,Plasticities, Brain,Plasticities, Neural,Plasticities, Neuronal,Plasticities, Synaptic,Plasticity, Brain,Plasticity, Neural,Plasticity, Synaptic,Pruning, Axon,Pruning, Axonal,Pruning, Dendrite,Pruning, Dendritic,Pruning, Neurite,Pruning, Neuronal,Pruning, Synaptic,Prunings, Axon,Prunings, Axonal,Prunings, Dendrite,Prunings, Dendritic,Prunings, Neurite,Prunings, Neuronal,Prunings, Synaptic,Remodeling, Dendritic,Remodeling, Neuronal,Remodeling, Neuronal Network,Remodelings, Dendritic,Remodelings, Neuronal,Remodelings, Neuronal Network,Synaptic Plasticities,Synaptic Prunings
D009799	Ocular Physiological Phenomena	Processes and properties of the EYE as a whole or of any of its parts.	Ocular Physiologic Processes,Ocular Physiological Processes,Ocular Physiology,Eye Physiology,Ocular Physiologic Process,Ocular Physiological Concepts,Ocular Physiological Phenomenon,Ocular Physiological Process,Physiology of the Eye,Physiology, Ocular,Visual Physiology,Concept, Ocular Physiological,Concepts, Ocular Physiological,Ocular Physiological Concept,Phenomena, Ocular Physiological,Phenomenon, Ocular Physiological,Physiologic Process, Ocular,Physiologic Processes, Ocular,Physiological Concept, Ocular,Physiological Concepts, Ocular,Physiological Process, Ocular,Physiological Processes, Ocular,Physiology, Eye,Physiology, Visual,Process, Ocular Physiologic,Process, Ocular Physiological,Processes, Ocular Physiologic,Processes, Ocular Physiological
D009801	Oculomotor Muscles	The muscles that move the eye. Included in this group are the medial rectus, lateral rectus, superior rectus, inferior rectus, inferior oblique, superior oblique, musculus orbitalis, and levator palpebrae superioris.	Extraocular Muscles,Extraocular Rectus Muscles,Inferior Oblique Extraocular Muscle,Inferior Oblique Muscles,Levator Palpebrae Superioris,Musculus Orbitalis,Oblique Extraocular Muscles,Oblique Muscle, Inferior,Oblique Muscle, Superior,Oblique Muscles, Extraocular,Rectus Muscles, Extraocular,Superior Oblique Extraocular Muscle,Superior Oblique Muscle,Extraocular Muscle,Extraocular Muscle, Oblique,Extraocular Muscles, Oblique,Extraocular Oblique Muscle,Extraocular Oblique Muscles,Extraocular Rectus Muscle,Inferior Oblique Muscle,Muscle, Oculomotor,Muscles, Oculomotor,Oblique Extraocular Muscle,Oblique Muscle, Extraocular,Oblique Muscles, Inferior,Oblique Muscles, Superior,Oculomotor Muscle,Rectus Muscle, Extraocular,Superior Oblique Muscles
D009802	Oculomotor Nerve	The 3d cranial nerve. The oculomotor nerve sends motor fibers to the levator muscles of the eyelid and to the superior rectus, inferior rectus, and inferior oblique muscles of the eye. It also sends parasympathetic efferents (via the ciliary ganglion) to the muscles controlling pupillary constriction and accommodation. The motor fibers originate in the oculomotor nuclei of the midbrain.	Cranial Nerve III,Third Cranial Nerve,Nerve III,Nervus Oculomotorius,Cranial Nerve IIIs,Cranial Nerve, Third,Cranial Nerves, Third,Nerve IIIs,Nerve, Oculomotor,Nerve, Third Cranial,Nerves, Oculomotor,Nerves, Third Cranial,Oculomotor Nerves,Oculomotorius, Nervus,Third Cranial Nerves
D002452	Cell Count	The number of CELLS of a specific kind, usually measured per unit volume or area of sample.	Cell Density,Cell Number,Cell Counts,Cell Densities,Cell Numbers,Count, Cell,Counts, Cell,Densities, Cell,Density, Cell,Number, Cell,Numbers, Cell
D000367	Age Factors	Age as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or the effect of a circumstance. It is used with human or animal concepts but should be differentiated from AGING, a physiological process, and TIME FACTORS which refers only to the passage of time.	Age Reporting,Age Factor,Factor, Age,Factors, Age
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia