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Wiley Interdisciplinary Reviews.... 2014The pathway that generates the dorsal-ventral (DV) axis of the Drosophila embryo has been the subject of intense investigation over the previous three decades. The... (Review)
Review
UNLABELLED
The pathway that generates the dorsal-ventral (DV) axis of the Drosophila embryo has been the subject of intense investigation over the previous three decades. The initial asymmetric signal originates during oogenesis by the movement of the oocyte nucleus to an anterior corner of the oocyte, which establishes DV polarity within the follicle through signaling between Gurken, the Drosophila Transforming Growth Factor (TGF)-α homologue secreted from the oocyte, and the Drosophila Epidermal Growth Factor Receptor (EGFR) that is expressed by the follicular epithelium cells that envelop the oocyte. Follicle cells that are not exposed to Gurken follow a ventral fate and express Pipe, a sulfotransferase that enzymatically modifies components of the inner vitelline membrane layer of the eggshell, thereby transferring DV spatial information from the follicle to the egg. These ventrally sulfated eggshell proteins comprise a localized cue that directs the ventrally restricted formation of the active Spätzle ligand within the perivitelline space between the eggshell and the embryonic membrane. Spätzle activates Toll, a transmembrane receptor in the embryonic membrane. Transmission of the Toll signal into the embryo leads to the formation of a ventral-to-dorsal gradient of the transcription factor Dorsal within the nuclei of the syncytial blastoderm stage embryo. Dorsal controls the spatially specific expression of a large constellation of zygotic target genes, the Dorsal gene regulatory network, along the embryonic DV circumference. This article reviews classic studies and integrates them with the details of more recent work that has advanced our understanding of the complex pathway that establishes Drosophila embryo DV polarity. For further resources related to this article, please visit the WIREs website.
CONFLICT OF INTEREST
The authors have declared no conflicts of interest for this article.
Topics: Animals; Body Patterning; Drosophila; Epistasis, Genetic; Gene Expression Regulation, Developmental; Gene Regulatory Networks
PubMed: 25124754
DOI: 10.1002/wdev.138 -
Seminars in Pediatric Surgery Aug 2010Ventral body wall defects include ectopia cordis, bladder exstrophy, and the abdominal wall malformations gastroschisis and omphalocele. The etiology of ectopia cordis,... (Review)
Review
Ventral body wall defects include ectopia cordis, bladder exstrophy, and the abdominal wall malformations gastroschisis and omphalocele. The etiology of ectopia cordis, gastroschisis, and bladder exstrophy is not known, but they may be linked to abnormalities in the lateral body wall folds responsible for closing the thoracic, abdominal, and pelvic portions of the ventral body wall. These folds form in the fourth week (postfertilization) of development as a combination of the parietal layer of lateral plate mesoderm and overlying ectoderm and must move ventrally to meet in the midline. There are differential rates of cell proliferation in the folds and asymmetries in their movement that may be involved in teratogenic effects of toxic factors. Also, the fusion process between the folds is complex, involving cell-to-cell adhesion, cell migration, and cell reorganization and all of these phenomena may be targets for disruption, leading to malformations. In this regard, closure of the ventral body wall is likened to neural tube closure and involves similar processes. It also encompasses a similar time frame during development, such that most neural tube and ventral body wall defects have their origins during the fourth week of development. Omphalocele is a separate entity whose etiology is known. This defect is attributed to a failure of gut loops to return to the body cavity after their normal physiological herniation into the umbilical cord from the 6th to 10th week of development. Thus, the origin of this defect is completely different from that of the ventral body wall malformations.
Topics: Abdominal Wall; Bladder Exstrophy; Child Development; Ectopia Cordis; Female; Follow-Up Studies; Gastroschisis; Hernia, Umbilical; Humans; Incidence; Infant, Newborn; Male
PubMed: 20610194
DOI: 10.1053/j.sempedsurg.2010.03.006 -
Neurosurgical Focus: Video Oct 2023The surgical management of ventral upper cervical meningiomas poses significant challenges due to their deep location and limited accessibility. These tumors have the...
The surgical management of ventral upper cervical meningiomas poses significant challenges due to their deep location and limited accessibility. These tumors have the potential to compress or involve nearby neurovascular structures, leading to various neurological complications including inferior cranial nerve palsy, motor deficits, and sensory disturbances such as hypoesthesia, paresthesia, and impaired coordination. To address this issue, surgical intervention through an anterolateral or far lateral approach has been recognized as the optimal treatment strategy. In this video, the authors present a detailed demonstration of the operative technique using an anterolateral upper cervical approach to safely resect a ventrally located C1-2 meningioma.
PubMed: 37854652
DOI: 10.3171/2023.6.FOCVID2377 -
Operative Neurosurgery (Hagerstown, Md.) Feb 2021Spinal cord herniation (SCH) is a rare condition that is typically of idiopathic origin. Although SCH is mostly found in the thoracic region because of a dural defect,...
Spinal cord herniation (SCH) is a rare condition that is typically of idiopathic origin. Although SCH is mostly found in the thoracic region because of a dural defect, there are some reports of cervical SCH following surgery or trauma.1-3 Spinal cord tethering can be a result of SCH or as a standalone issue.4,5 These conditions can lead to progressive neurological deficits, including numbness, gait disturbances, and decreased muscle strength, requiring surgical correction. There are limited reports of surgical procedures for ventral SCHs. Several reports exist using a ventral approach for intradural tumors, but it is not commonly employed because of the inability to obtain adequate dural closure.6 Much of the literature on SCH comes from idiopathic and congenital cases in the thoracic spine.7,8 Posterior and posterolateral approaches for a ventral thoracic SCH have been described, as well as an anterior approach for a ventral cervical SCH.9-12 In this video, we describe a posterior approach for a ventral cervical SCH. A 38-yr-old male presented with progressive cervical myelopathy 9 yr after a C2-C3 schwannoma resection requiring an anterior approach and corpectomy of C3 with partial corpectomies of C2 and C4. A preoperative magnetic resonance imaging showed a ventrally herniated spinal cord at the top of the C3 vertebral body and below the C4 vertebral body. Informed consent was obtained. The posterior surgical approach involved a C1-C5 laminectomy, sectioning the dentate ligament, ventral cord untethering, removal of residual tumor, and placement of a ventral sling. A significant improvement in sensory and motor function was observed postoperatively.
Topics: Cervical Cord; Cervical Vertebrae; Hernia; Humans; Male; Spinal Cord Diseases
PubMed: 33372993
DOI: 10.1093/ons/opaa340 -
Proceedings. Biological Sciences Dec 2023The ability to enrol for protection is an effective defensive strategy that has convergently evolved multiple times in disparate animal groups ranging from euarthropods...
The ability to enrol for protection is an effective defensive strategy that has convergently evolved multiple times in disparate animal groups ranging from euarthropods to mammals. Enrolment is a staple habit of trilobites, and their biomineralized dorsal exoskeleton offered a versatile substrate for the evolution of interlocking devices. However, it is unknown whether trilobites also featured ventral adaptations for enrolment. Here, we report ventral exoskeletal adaptations that facilitate enrolment in exceptionally preserved trilobites from the Middle Ordovician Walcott-Rust Quarry in New York State, USA. Walcott-Rust trilobites reveal the intricate three-dimensional organization of the non-biomineralized ventral anatomy preserved as calcite casts, including the spatial relationship between the articulated sternites (i.e. ventral exoskeletal plates) and the wedge-shaped protopodites. Enrolment in trilobites is achieved by ventrally dipping the anterior margin of the sternites during trunk flexure, facilitated by the presence of flexible membranes, and with the close coupling of the wedge-shaped protopodites. Comparisons with the ventral morphology of extant glomerid millipedes and terrestrial isopods reveal similar mechanisms used for enrolment. The wedge-shaped protopodites of trilobites closely resemble the gnathobasic coxa/protopodite of extant horseshoe crabs. We propose that the trilobites' wedge-shaped protopodite simultaneously facilitated tight enrolment and gnathobasic feeding with the trunk appendages.
Topics: Animals; Biological Evolution; Fossils; Arthropods; Horseshoe Crabs; New York; Mammals
PubMed: 38113938
DOI: 10.1098/rspb.2023.2212 -
Mechanisms of Development Jan 1997The idea that chordates, during their evolution, have inverted their dorsoventral body axis has recently gained substantial support. It has been shown that various... (Comparative Study)
Comparative Study Review
The idea that chordates, during their evolution, have inverted their dorsoventral body axis has recently gained substantial support. It has been shown that various dorsoventral patterning genes that are evolutionarily conserved between insects and vertebrates are expressed dorsally in insects, and ventrally in vertebrates, or vice versa. The ventral body side of insects thus seems to correspond to the dorsal body side of vertebrates, and these are nerve cord-bearing, neural body sides in both groups. In order to exclude that the inverted polarity of gene patterning activity is purely accidental, we compare here vertebrate and invertebrate blastula fate maps and their gastrulation patterns in the framework of early gene expression. From this comparison it appears that the neural body sides, 'ventral' in annelids or arthropods, and 'dorsal' in chordates, develop at similar positions with respect to the initial egg asymmetry. In addition, the formation of the neural body sides involves similar movements during gastrulation. We further suggest that the deuterostome gastrulation seen in today's chordates can be derived from a more ancestral gastrulation pattern seen in today's annelids and arthropods, and that the ventral midline cells of insects correspond to the dorsal midline cells of vertebrates.
Topics: Animals; Annelida; Arthropods; Blastocyst; Chordata, Nonvertebrate; Gastrula; Genes, Homeobox
PubMed: 9076674
DOI: 10.1016/s0925-4773(96)00620-x -
Aktuelle Probleme in Chirurgie Und... 1991
Review
Topics: Adult; Bone Plates; Bone Screws; Bone Transplantation; Female; Humans; Intervertebral Disc Displacement; Lumbar Vertebrae; Male; Middle Aged; Radiography; Spinal Fusion; Spondylitis; Transplantation, Autologous
PubMed: 1686359
DOI: No ID Found -
Operative Neurosurgery (Hagerstown, Md.) Dec 2020Ventral thoracic meningiomas are rare entities in which the spinal cord is attenuated and draped over the meningioma symmetrically. This is a challenging surgical entity...
Ventral thoracic meningiomas are rare entities in which the spinal cord is attenuated and draped over the meningioma symmetrically. This is a challenging surgical entity compared to typical intradural meningiomas, which nearly always eccentrically displace the cord. In these more common meningiomas, surgical access is fairly straightforward as the meningioma is often visualized upon opening the meninges. Resection can be more safely performed with the cord largely shifted. In cases of ventral meningioma, the tumor is hidden ventral to the spinal cord, and techniques to safely mobilize the spinal cord must be utilized. We demonstrate that an entirely posterior approach allows complete resection of a ventrally situated mass. After careful identification and sectioning of the dentate ligament at multiple levels on the right side of the canal, we then suture and rotate the dentate ligament at each site, thereby allowing progressive visualization of the ventral meningioma. A narrow, but viable, working corridor to the tumor allows safe debulking. Once it is felt that the tumor can no longer be safely excised through the created corridor, we then disconnect our dentate sutures and move to the other side of the canal. Similarly, the dentate is sectioned and sutured so that the contralateral aspect of the meningioma can be visualized and debulked. The tumor can then be safely removed. A standard posterior approach and midline durotomy allows this bilateral approach to a ventrally situated meningioma and, therefore, in our mind, represents a safe and also highly effective road to resection. Patient consent was obtained prior to publication.
Topics: Humans; Meningeal Neoplasms; Meningioma; Neurosurgical Procedures; Spinal Cord Neoplasms
PubMed: 32823286
DOI: 10.1093/ons/opaa252 -
Current Opinion in Neurobiology Apr 2013Language processing is supported by different regions located in separate parts of the brain. A crucial condition for these regions to function as a network is the... (Review)
Review
Language processing is supported by different regions located in separate parts of the brain. A crucial condition for these regions to function as a network is the information transfer between them. This is guaranteed by dorsal and ventral pathways connecting prefrontal and temporal language-relevant regions. Based on functional brain imaging studies, these pathways' language functions can be assigned indirectly. Dorsally, one pathway connecting the temporal cortex (TC) and premotor cortex supports speech repetition, another one connecting the TC and posterior Broca's area supports complex syntactic processes. Ventrally, the uncinate fascile and the inferior fronto-occipital fascile subserve semantic and basic syntactic processes. Thus, the available evidence points towards a neural language network with at least two dorsal and two ventral pathways.
Topics: Brain; Brain Mapping; Functional Laterality; Humans; Language; Neural Pathways
PubMed: 23146876
DOI: 10.1016/j.conb.2012.10.002