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Proceedings of the National Academy of... Oct 2019Observing the structure and regeneration of the myelin sheath in peripheral nerves following injury and during repair would help in understanding the pathogenesis and...
Observing the structure and regeneration of the myelin sheath in peripheral nerves following injury and during repair would help in understanding the pathogenesis and treatment of neurological diseases caused by an abnormal myelin sheath. In the present study, transmission electron microscopy, immunofluorescence staining, and transcriptome analyses were used to investigate the structure and regeneration of the myelin sheath after end-to-end anastomosis, autologous nerve transplantation, and nerve tube transplantation in a rat model of sciatic nerve injury, with normal optic nerve, oculomotor nerve, sciatic nerve, and Schwann cells used as controls. The results suggested that the double-bilayer was the structural unit that constituted the myelin sheath. The major feature during regeneration was the compaction of the myelin sheath, wherein the distance between the 2 layers of cell membrane in the double-bilayer became shorter and the adjacent double-bilayers tightly closed together and formed the major dense line. The expression level of myelin basic protein was positively correlated with the formation of the major dense line, and the compacted myelin sheath could not be formed without the anchoring of the lipophilin particles to the myelin sheath.
Topics: Animals; Axons; Myelin Sheath; Nerve Regeneration; Peripheral Nerve Injuries; Rats
PubMed: 31611410
DOI: 10.1073/pnas.1910292116 -
The Kurume Medical Journal Mar 2022An ossified left petroclinoid ligament was found during routine dissection of the skull base in an adult male cadaver. The petroclinoid ligament is clinically and... (Review)
Review
An ossified left petroclinoid ligament was found during routine dissection of the skull base in an adult male cadaver. The petroclinoid ligament is clinically and surgically important given its anatomical relationships to cranial nerves III, V, and VI, so its ossification is a risk factor for injuries due to trauma, increased intracranial pressure, and vascular and tumor compression resulting in abducens and oculomotor palsies. The causes of petroclinoid ligament ossification are yet to be completely elucidated although several reports have associated them with age-related and physiological processes. Assessing the integrity of the petroclinoid ligament is important during skull base surgical interventions to avoid postoperative complications. Therefore, this paper reviews the petroclinoid ligament and its variation, the ossified petroclinoid ligament.
Topics: Abducens Nerve; Adult; Cadaver; Dissection; Humans; Ligaments; Male; Osteogenesis
PubMed: 35095019
DOI: 10.2739/kurumemedj.MS671007 -
Brain Sciences Nov 2021Parinaud's syndrome involves dysfunction of the structures of the dorsal midbrain. We investigated the pathophysiology related to the signs and symptoms to better... (Review)
Review
Parinaud's syndrome involves dysfunction of the structures of the dorsal midbrain. We investigated the pathophysiology related to the signs and symptoms to better understand the symptoms of Parinaud's syndrome: diplopia, blurred vision, visual field defects, ptosis, squint, and ataxia, and Parinaud's main signs of upward gaze paralysis, upper eyelid retraction, convergence retraction nystagmus (CRN), and pseudo-Argyll Robertson pupils. In upward gaze palsy, three structures are disrupted: the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF), interstitial nucleus of Cajal (iNC), and the posterior commissure. In CRN, there is a continuous discharge of the medial rectus muscle because of the lack of inhibition of supranuclear fibers. In Collier's sign, the posterior commissure and the iNC are mainly involved. In the vicinity of the iNC, there are two essential groups of cells, the M-group cells and central caudal nuclear (CCN) group cells, which are important for vertical gaze, and eyelid control. Overstimulation of the M group of cells and increased firing rate of the CCN group causing eyelid retraction. External compression of the posterior commissure, and pretectal area causes pseudo-Argyll Robertson pupils. Pseudo-Argyll Robertson pupils constrict to accommodation and have a slight response to light (miosis) as opposed to Argyll Robertson pupils were there is no response to a light stimulus. In Parinaud's syndrome patients conserve a slight response to light because an additional pathway to a pupillary light response that involves attention to a conscious bright/dark stimulus. Diplopia is mainly due to involvement of the trochlear nerve (IVth cranial nerve. Blurry vision is related to accommodation problems, while the visual field defects are a consequence of chronic papilledema that causes optic neuropathy. Ptosis in Parinaud's syndrome is caused by damage to the oculomotor nerve, mainly the levator palpebrae portion. We did not find a reasonable explanation for squint. Finally, ataxia is caused by compression of the superior cerebellar peduncle.
PubMed: 34827468
DOI: 10.3390/brainsci11111469