Axons Giving Rise to the Palisade Endings of Feline Extraocular Muscles Display Motor Features

Zimmermann, Lars; Morado-Díaz, Camilo J.; Carrizosa, María A. Davis‐López de; Cruz, Rosa R. de la; May, Paul J.; Streicher, Johannes; Pastor, Ángel M.; Blumer, Roland

doi:10.1523/jneurosci.4116-12.2013

Cited by 48 publications

(63 citation statements)

References 30 publications

(56 reference statements)

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“…20 These findings strongly suggest that palisade endings arise from MIF motoneurons in the EOM motor nuclei although receptors for cholinergic transmission have not been found in palisade endings so far with the exception of rabbit and rat. 10,20 Following tracer injection into the distal myotendinous junction (the region of the palisade endings), two populations of neurons have been retrogradely labeled at the periphery of the oculomotor nucleus, i.e., multipolar motor-like neurons and spindle shaped sensory-like neurons. 32 It has been suggested that the latter group are the source of palisade endings.…”

Section: Developmental Support For a Mif Motoneuronpalisade Ending Comentioning

confidence: 83%

Section: Developmental Support For a Mif Motoneuronpalisade Ending Comentioning

confidence: 89%

“…[18][19][20] Combining anterograde tracer labeling and molecular analyses, we demonstrated that axons supplying palisade endings established several motor contacts alongside the muscle fibers in a manner equal to that of en grappe motor terminals on MIFs. 20 These findings strongly suggest that palisade endings arise from MIF motoneurons in the EOM motor nuclei although receptors for cholinergic transmission have not been found in palisade endings so far with the exception of rabbit and rat. 10,20 Following tracer injection into the distal myotendinous junction (the region of the palisade endings), two populations of neurons have been retrogradely labeled at the periphery of the oculomotor nucleus, i.e., multipolar motor-like neurons and spindle shaped sensory-like neurons.…”

Section: Developmental Support For a Mif Motoneuronpalisade Ending Comentioning

confidence: 89%

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Palisade Endings of Extraocular Muscles Develop Postnatally Following Different Time Courses

Blumer¹,

Streicher

Carrizosa

et al. 2017

Invest. Ophthalmol. Vis. Sci.

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PURPOSE. To analyze in a frontal-eyed mammal (cat) the postnatal development of palisade endings in extraocular muscles (EOMs) and to compare the spatiotemporal and quantitative patterns of palisade endings among individual rectus muscles. METHODS.Cats of different ages ranging from birth to adult stage were studied. EOM wholemount preparations were fluorescently labeled using six combinations of triple staining and analyzed in the confocal laser scanning microscope. RESULTS.Palisade endings developed postnatally and passed in each rectus muscle through the same, three developmental steps but in a heterochronic sequence and to a different final density per muscle. Specifically, palisade ending development was first completed in the medial rectus and later in the inferior, lateral, and superior rectus. The highest density of palisade endings was observed in the medial rectus and the lowest in the lateral rectus whereas values for the inferior and superior rectus were in between. Palisade endings expressed high levels of growth associated protein 43 during development and were supplied by axons that established motor terminals.CONCLUSIONS. Cats open their eyes 7 to 10 days after birth and later develop a complex threedimensional visuomotor climbing and jumping behavior depending on accurate binocular vision and fine tuning of the ocular movements. Our findings indicate that palisade ending development correlates with important landmarks in visuomotor behavior and provide support for our previous notion that palisade endings play an important role for convergence eye movements in frontal-eyed species.

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Section: Developmental Support For a Mif Motoneuronpalisade Ending Comentioning

confidence: 83%

Section: Developmental Support For a Mif Motoneuronpalisade Ending Comentioning

confidence: 89%

Section: Developmental Support For a Mif Motoneuronpalisade Ending Comentioning

confidence: 89%

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Palisade Endings of Extraocular Muscles Develop Postnatally Following Different Time Courses

Blumer¹,

Streicher

Carrizosa

et al. 2017

Invest. Ophthalmol. Vis. Sci.

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“…Intrinsic (molecular) differences may account for the selective vulnerability of α-MNs versus γ-MNs in ALS, but other distinctions between these MN subtypes may play a role also. For example, unlike α-MNs, γ-MNs do not receive monosynaptic excitatory inputs from I A proprioceptive afferents; in this way, γ-MNs are like oculomotor neurons, another population of MNs selectively spared in ALS (33,34). Moreover, MNs in Onuf's nucleus that control defecation, micturition, and ejaculation are also preserved in ALS (35), and, as is consistent with excitatory proprioceptive inputs having a role in MN degeneration in ALS, these MNs do not receive vesicular glutamate transporter 1 (VGluT1) inputs, as shown in a caudal (L6) lumbar section of the mouse spinal cord (Fig.…”

Section: G93amentioning

confidence: 99%

Gamma motor neurons survive and exacerbate alpha motor neuron degeneration in ALS

Lalancette–Hébert

Sharma

Lyashchenko

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

106

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The molecular and cellular basis of selective motor neuron (MN) vulnerability in amyotrophic lateral sclerosis (ALS) is not known. In genetically distinct mouse models of familial ALS expressing mutant superoxide dismutase-1 (SOD1), TAR DNA-binding protein 43 (TDP-43), and fused in sarcoma (FUS), we demonstrate selective degeneration of alpha MNs (α-MNs) and complete sparing of gamma MNs (γ-MNs), which selectively innervate muscle spindles. Resistant γ-MNs are distinct from vulnerable α-MNs in that they lack synaptic contacts from primary afferent (I A ) fibers. Elimination of these synapses protects α-MNs in the SOD1 mutant, implicating this excitatory input in MN degeneration. Moreover, reduced I A activation by targeted reduction of γ-MNs in SOD1G93A mutants delays symptom onset and prolongs lifespan, demonstrating a pathogenic role of surviving γ-MNs in ALS. This study establishes the resistance of γ-MNs as a general feature of ALS mouse models and demonstrates that synaptic excitation of MNs within a complex circuit is an important determinant of relative vulnerability in ALS.ALS | motor neuron disease | gamma motor neuron | fusimotor A myotrophic lateral sclerosis (ALS) is a fatal disorder characterized by selective motor neuron (MN) degeneration in the brain and spinal cord (1). Not all MN subtypes are equally vulnerable in ALS, and specific subpopulations of MNs, including neurons in the oculomotor and Onuf's nuclei, are preserved even at late stages of disease (2-8). The sparing of these motor pools in ALS is complete, but within the motor pools that are affected the degree to which distinct functional subtypes of MNs are vulnerable varies: fast-fatigable motor neurons are the first to degenerate in ALS patients (9) and in mutant SOD1 mice (10, 11), followed by fatigue-resistant motor units, whereas slow motor units are preserved until late in the course of the disease (12). The reason for the selective vulnerability of distinct subpopulations of MNs in ALS is not known, but factors that determine the unique features of individual MN subtypes, including their size, morphology, and membrane properties, may play a role. In addition, the factors that influence MN vulnerability in ALS may relate to the organization and function of synaptic inputs on each MN subtype that regulate MN activity and control motor output. How the connectivity of MNs within complex motor circuits influences their relative vulnerability in ALS is not known.Extraocular muscles composed of multiple (fast-, intermediate-, and slow-twitch) fiber types (13) and innervated by ALS

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“…30 Other studies, using central tracer injections in non-human primates, also support a motor function, but suggest that tendon endings and 'en grappe' terminals arise from separate neurons located around the periphery of the motor nuclei of EOMs. 32,33 Even though it cannot be precluded that myotendinous nerve endings have a sensory function, 2,34 the notion that muscle spindles represents the only structures with proprioceptive potency seem to gain growing support. 35 …”

Section: Myotendinous Nerve Endingsmentioning

confidence: 99%

How does the structure of extraocular muscles and their nerves affect their function?

Bruenech

Haugen²

2014

Eye

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The sensory and motor control of human extraocular muscles (EOMs) have been subjected to considerable speculation in ophthalmic literature, often related to infranuclear structures such as the unique complement of muscle fibres and their associated sensory organs. The intrafusal fibres do not resemble their somatic counterparts and their peculiar morphology has raised questions about their proprioceptive capacity. No Golgi tendon organs have so far been observed and the myotendinous nerve endings, previously assumed to convey sensory information, have recently been argued to merely represent constituents of the efferent innervation serving the multiply innervated muscles fibres. These observations raise questions about the overall capacity to monitor the activity created by the generous efferent nerve supply observed in these muscles. Furthermore, the argued independent activity of muscular layers and compartments suggest that the required feedback must be highly structured and more specific than previously assumed. Yet, uncertainty about the source of such information remains. The purpose of this paper is to provide a short review of neuromuscular properties of human extraocular muscles. Their functional implications and the most reputable sources of proprioception will also be discussed. The promoted views are based on pertinent literature and previous research undertaken by the authors.

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Axons Giving Rise to the Palisade Endings of Feline Extraocular Muscles Display Motor Features

Cited by 48 publications

References 30 publications

Palisade Endings of Extraocular Muscles Develop Postnatally Following Different Time Courses

Palisade Endings of Extraocular Muscles Develop Postnatally Following Different Time Courses

Gamma motor neurons survive and exacerbate alpha motor neuron degeneration in ALS

How does the structure of extraocular muscles and their nerves affect their function?

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