Topic
Commissure
About: Commissure is a research topic. Over the lifetime, 576 publications have been published within this topic receiving 21377 citations.
Papers published on a yearly basis
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Papers
TL;DR: At 1 day, the zebrafish brain is impressively simple, with a few small, well-separated tracts but by 2 days the brain is already considerably more complex, supporting the notion that other axons play a crucial role in the guidance of early central nervous system (CNS).
Abstract: We have examined neuronal differentiation and the formation of axon tracts in the embryonic forebrain and midbrain of the zebrafish, between 1 and 2 days postfertilisation. Axons were visualised with three techniques; immunocytochemistry (using HNK-1 and antiacetylated tubulin antibodies) and horseradish peroxidase (HRP) labelling in whole-mounted brains, and transmission electron microscopy. Differentiation was monitored by histochemical staining for acetylcholinesterase (AChE). These independent methods demonstrated that a simple grid of tracts and commissures forms the initial axon scaffold of the brain. At 1 day, the olfactory nerve, four commissures, their associated tracts and three other non-commissural tracts are present. By 2 days, these tracts and commissures have all greatly enlarged and, in addition, the optic nerve and tract, and three new commissures and their associated tracts have been added. Small applications of HRP at various sites revealed the origins and projections of some of these earliest axons. Retrogradely labelled cell bodies originated from regions that were also positive for AChE activity. At 1 day, HRP-labelled axons were traced: (1) from the olfactory placode through the olfactory nerve to the dorsal telencephalon; (2) from the telencephalon into the tract of the anterior commissure and also to the postoptic region of the diencephalon; (3) from the hindbrain through the ventral midbrain and diencephalon to the postoptic commissure; (4) from the dorsal diencephalon (in or near the epiphysis) to the tract of the postoptic commissure; (5) from ventral and rostral midbrain through the posterior commissure. Three new projections were demonstrated at 2 days: (1) from the retina through the tract of the postoptic commissure to the tectum; (2) from the telencephalon to the contralateral diencephalon; and (3) from the telencephalon to the ventral flexure. These results show that at 1 day, the zebrafish brain is impressively simple, with a few small, well-separated tracts but by 2 days the brain is already considerably more complex. Most of the additional axons added onto pre-existent tracts rather than pioneered new ones supporting the notion that other axons play a crucial role in the guidance of early central nervous system (CNS) axons.
437 citations
Patent•
16 Jun 1997TL;DR: A stent for receiving and supporting a tissue heart valve for ultimate implantation into a human, the heart valve including tissue leaflets joined at circumferentially spaced commissures, wherein the stent includes at least one commissure support post and at least sinus support structure each sinus structure being disposed between but not functionally connected to an adjacent support post as mentioned in this paper.
Abstract: A stent for receiving and supporting a tissue heart valve for ultimate implantation into a human, the heart valve including tissue leaflets joined at circumferentially spaced commissures, wherein the stent includes at least one commissure support post and at least one sinus support structure each sinus support structure being disposed between but not functionally connected to an adjacent commissure support post.
393 citations
TL;DR: The number, types, and distribution of distinct classes of axons and glia in four cerebral commissures of the adult rhesus monkey (Macaca mulatta) were determined using electron microscopic and immunocytochemical methods.
Abstract: The number, types, and distribution of distinct classes of axons and glia in four cerebral commissures of the adult rhesus monkey (Macaca mulatta) were determined using electron microscopic and immunocytochemical methods. The two neocortical commissures, the corpus callosum, and the anterior commissure contain small but cytologically distinct archicortical components: the hippocampal commissure, which lies ventral to the splenium of the corpus callosum, and the basal telencephalic commissure, which forms a small crescent at the anterior margin of the anterior commissure. Each archicortical pathway is delineated from the adjacent neocortical commissure by a glial capsule. The glia cells that form this border are immunoreactive with antisera directed against glial fibrillary acidic protein (GFAP) and issue long processes that form numerous desmosomal junctions with one another. Braids of these glial processes envelop axonal fascicles within the archicortical commissures. In contrast, the GFAP-positive cells of the corpus callosum and anterior commissure are randomly distributed cells with relatively short stellate processes that do not form boundaries around axon fascicles. Quantitative electron microscopic analysis reveals that approximately 60 million axons connect the two cerebral hemispheres: the corpus callosum contains 56.0 million +/- 3.8 million axons (n = 8), the anterior commissure contains 3.15 million +/- 0.24 million axons (n = 8), the hippocampal commissure has 237,000 axons +/- 31,000 (n = 6), and the basal telencephalic commissure has 193,000 axons +/- 28,000 (n = 5). The number of axons is not directly proportional to the cross-sectional area in any of the commissures because of variation in axonal composition. On the basis of an estimate of approximately 3 billion neurons in the monkey cortex (Shariff, '53), we estimate that between 2 and 3% of all cortical neurons project to the opposite cerebral hemisphere. Subregions of the corpus callosum as well as each of the other commissures consist of characteristic subsets of five classes of axons and contain different proportions of myelinated to unmyelinated fibers. The largest myelinated axons and the smallest proportion of unmyelinated axons (approximately 6%) are found in regions of the corpus callosum that carry projections from primary sensory cortices, whereas the smallest myelinated axons and largest proportion of unmyelinated axons (approximately 30%) are found in regions of the corpus callosum that carry projections from association cortices. Axon composition in the anterior commissure is uniform and resembles that of callosal sectors that contain association projections.(ABSTRACT TRUNCATED AT 400 WORDS)
386 citations
TL;DR: This work has identified two Drosophila homologs of this protein family (Netrin-A and Netrin-B) that are dynamically expressed throughout embryogenesis, including CNS midline expression at the time of commissure formation, confirming an important role for Drosophile Netrins in commissural growth cone guidance.
339 citations
Patent•
17 Aug 1981
TL;DR: In this paper, a prosthetic heart valve including a frame having a plurality of commissure and resilient supports, and valve leaflets is attached to the resilient supports and the resilient support lies radially outwardly of the commissures, respectively.
Abstract: A prosthetic heart valve including a frame having a plurality of commissure supports, a plurality of resilient supports, and a plurality of valve leaflets. The valve leaflets are attached to the resilient supports, and the resilient supports lie radially outwardly of the commissure supports, respectively. When in use, the valve is subjected to forces which are used to clamp the valve leaflets between the resilient supports and the commissure supports to augment whatever other leaflet attachment techniques may be used.
315 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2025 | 24 |
| 2024 | 28 |
| 2023 | 90 |
| 2022 | 111 |
| 2021 | 22 |
| 2020 | 22 |