An autopsy study of a familial oculopharyngeal muscular dystrophy (OPMD) with distal spread and neurogenic involvement

An 81-year-old man from a family with a history of oculopharyngeal muscular dystrophy (OPMD) involving 6 members over 4 generations is described. The patient first noted drooping of his eyelids at the age of 65. Dysphagia and dysarthria occurred soon thereafter. At age 78, impairment of gait developed and progressive wasting occurred in the limbs with an initial distal distribution. Electromyography of several limb muscles displayed a mixed myopathic and neurogenic pattern with giant potentials. Examination at autopsy revealed slight loss of neurons in the anterior horns of the spinal cord, with scanty ghost cells, neuronophagia, and central chromatolysis. By light microscopy the limb muscles showed moderate small-group atrophy with severe myopathy and target fibers. The viscerocranial muscles, including the ocular, vocal, and tongue muscles, demonstrated only myopathic change with the typical features of progressive muscular dystrophy. Advanced replacement by fibrous connective tissue and fat had occurred in both the viscerocranial and the lower limb muscles. The significance of neurogenic involvement in OPMD is discussed

Cellular and Molecular Anatomy of the Human Neuromuscular Junction

The neuromuscular junction (NMJ) plays a fundamental role in transferring information from lower motor neuron to skeletal muscle to generate movement. It is also an experimentally accessible model synapse routinely studied in animal models to explore fundamental aspects of synaptic form and function. Here, we combined morphological techniques, super-resolution imaging, and proteomic profiling to reveal the detailed cellular and molecular architecture of the human NMJ. Human NMJs were significantly smaller, less complex, and more fragmented than mouse NMJs. In contrast to mice, human NMJs were also remarkably stable across the entire adult lifespan, showing no signs of age-related degeneration or remodeling. Super-resolution imaging and proteomic profiling revealed distinctive distribution of active zone proteins and differential expression of core synaptic proteins and molecular pathways at the human NMJ. Taken together, these findings reveal human-specific cellular and molecular features of the NMJ that distinguish them from comparable synapses in other mammalian species

NMJ-morph reveals principal components of synaptic morphology influencing structure–function relationships at the neuromuscular junction

The ability to form synapses is one of the fundamental properties required by the mammalian nervous system to generate network connectivity. Structural and functional diversity among synaptic populations is a key hallmark of network diversity, and yet we know comparatively little about the morphological principles that govern variability in the size, shape and strength of synapses. Using the mouse neuromuscular junction (NMJ) as an experimentally accessible model synapse, we report on the development of a robust, standardized methodology to facilitate comparative morphometric analysis of synapses (‘NMJ-morph’). We used NMJ-morph to generate baseline morphological reference data for 21 separate pre- and post-synaptic variables from 2160 individual NMJs belonging to nine anatomically distinct populations of synapses, revealing systematic differences in NMJ morphology between defined synaptic populations. Principal components analysis revealed that overall NMJ size and the degree of synaptic fragmentation, alongside pre-synaptic axon diameter, were the most critical parameters in defining synaptic morphology. ‘Average’ synaptic morphology was remarkably conserved between comparable synapses from the left and right sides of the body. Systematic differences in synaptic morphology predicted corresponding differences in synaptic function that were supported by physiological recordings, confirming the robust relationship between synaptic size and strength

Apoptosis and proliferation in the trigeminal placode

The neurogenic trigeminal placode develops from the crescent-shaped panplacodal primordium which delineates the neural plate anteriorly. We show that, in Tupaia belangeri, the trigeminal placode is represented by a field of focal ectodermal thickenings which over time changes positions from as far rostral as the level of the forebrain to as far caudal as opposite rhombomere 3. Delamination proceeds rostrocaudally from the ectoderm adjacent to the rostral midbrain, and contributes neurons to the trigeminal ganglion as well as to the ciliary ganglion/oculomotor complex. Proliferative events are centered on the field prior to the peak of delamination. They are preceded, paralleled and, finally, outnumbered by apoptotic events which proceed rostrocaudally from non-delaminating to delaminating parts of the field. Apoptosis persists upon regression of the placode, thereby exhibiting a massive “wedge” of apoptotic cells which includes the postulated position of the “ventrolateral postoptic placode” (Lee et al. in Dev Biol 263:176–190, 2003), merges with groups of lens-associated apoptotic cells, and disappears upon lens detachment. In conjunction with earlier work (Washausen et al. in Dev Biol 278:86–102, 2005) our findings suggest that apoptosis contributes repeatedly to the disintegration of the panplacodal primordium, to the elimination of subsets of premigratory placodal neuroblasts, and to the regression of placodes

Unclassified familial myopathy resembling steinert disease, without myotonia

A familial myopathy with predominantly proximal muscle atrophy is described. Although several clinical features such as sternomastoid and brachioradialis muscle involvement suggested Steinert disease, myotonia was not demonstrated by clinical examination or EMG. Histological data were consistent with myotonic dystrophy.SCOPUS: ar.jFLWNAinfo:eu-repo/semantics/publishe

Les modifications de l'innervation motrice dans les myopathies acquises

info:eu-repo/semantics/publishe

Morphologie de la jonction neuro-musculaire

info:eu-repo/semantics/publishe

Histology of the myoneural junction in myopathies

info:eu-repo/semantics/publishe