dorsal midline
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Author(s):  
Kouhei Oonuma ◽  
Maho Yamamoto ◽  
Naho Moritsugu ◽  
Nanako Okawa ◽  
Megumi Mukai ◽  
...  

In vertebrate embryos, dorsal midline tissues, including the notochord, the prechordal plate, and the floor plate, play important roles in patterning of the central nervous system, somites, and endodermal tissues by producing extracellular signaling molecules, such as Sonic hedgehog (Shh). In Ciona, hedgehog.b, one of the two hedgehog genes, is expressed in the floor plate of the embryonic neural tube, while none of the hedgehog genes are expressed in the notochord. We have identified a cis-regulatory region of hedgehog.b that was sufficient to drive a reporter gene expression in the floor plate. The hedgehog.b cis-regulatory region also drove ectopic expression of the reporter gene in the endodermal strand, suggesting that the floor plate and the endodermal strand share a part of their gene regulatory programs. The endodermal strand occupies the same topographic position of the embryo as does the vertebrate hypochord, which consists of a row of single cells lined up immediately ventral to the notochord. The hypochord shares expression of several genes with the floor plate, including Shh and FoxA, and play a role in dorsal aorta development. Whole-embryo single-cell transcriptome analysis identified a number of genes specifically expressed in both the floor plate and the endodermal strand in Ciona tailbud embryos. A Ciona FoxA ortholog FoxA.a is shown to be a candidate transcriptional activator for the midline gene battery. The present findings suggest an ancient evolutionary origin of a common developmental program for the midline structures in Olfactores.


2021 ◽  
Vol 7 (24) ◽  
pp. eabg5968
Author(s):  
Baruch Haimson ◽  
Oren Meir ◽  
Reut Sudakevitz-Merzbach ◽  
Gerard Elberg ◽  
Samantha Friedrich ◽  
...  

Flight in birds evolved through patterning of the wings from forelimbs and transition from alternating gait to synchronous flapping. In mammals, the spinal midline guidance molecule ephrin-B3 instructs the wiring that enables limb alternation, and its deletion leads to synchronous hopping gait. Here, we show that the ephrin-B3 protein in birds lacks several motifs present in other vertebrates, diminishing its affinity for the EphA4 receptor. The avian ephrin-B3 gene lacks an enhancer that drives midline expression and is missing in galliforms. The morphology and wiring at brachial levels of the chicken embryonic spinal cord resemble those of ephrin-B3 null mice. Dorsal midline decussation, evident in the mutant mouse, is apparent at the chick brachial level and is prevented by expression of exogenous ephrin-B3 at the roof plate. Our findings support a role for loss of ephrin-B3 function in shaping the avian brachial spinal cord circuitry and facilitating synchronous wing flapping.


2021 ◽  
Vol 48 (3) ◽  
pp. 254-260
Author(s):  
Beatriz Hatsue Kushida-Contreras ◽  
Miguel Angel Gaxiola-García

Background Myelomeningocele is a frequently seen condition at tertiary care hospitals. Its treatment involves a variety of plastic reconstructive techniques. Herein, we present a series of myelomeningocele patients treated using keystone flaps.Methods We gathered information regarding soft tissue reconstruction and the use of bilateral keystone flaps to treat myelomeningocele patients. We obtained data from clinical records and recorded the demographic characteristics of mothers and children with the condition. The size, level of defect, and complications detected during the follow-up were analyzed.Results A series of seven patients who underwent bilateral keystone flaps for myelomeningocele closure was analyzed. There were no cases of midline or major dehiscence, flap loss, necrosis, surgical site infections, or cerebrospinal fluid leakage. No revision procedures were performed. Minor complications included one case with minimal seroma and three cases with areas of peripheral dehiscence that healed easily using conventional measures.Conclusions The use of keystone flaps is an adequate option for closure of dorsal midline soft tissue defects related to myelomeningocele. This technique offers predictable results with an acceptable spectrum of complications. Robust blood flow can be predicted based upon anatomical knowledge.


2021 ◽  
Author(s):  
Baruch Haimson ◽  
Oren Meir ◽  
Reut Sudakevitz-Merzbach ◽  
Gerard Elberg ◽  
Samantha Friedrich ◽  
...  

AbstractFlight in birds evolved through patterning of the wings from forelimbs and transition from alternating gait to synchronous flapping. In mammals, the spinal midline guidance molecule ephrin-B3 instructs the wiring that enables limb alternation, and its deletion leads to synchronous hopping gait. Here we show that the ephrin-B3 protein in birds lacks several motifs present in other vertebrates, diminishing its affinity for the EphA4 receptor. The avian ephrin-B3 gene lacks an enhancer that drives midline expression, and is missing in Galliformes. The morphology and wiring at brachial levels of the chick spinal cord resemble those of ephrin-B3 null mice. Importantly, dorsal midline decussation, evident in the mutant mouse, is apparent at the chick brachial level, and is prevented by expression of exogenous ephrin-B3 at the roof plate. Our findings support a role for loss of ephrin-B3 function in shaping the avian brachial spinal cord circuitry and facilitating synchronous wing flapping.TeaserWalking vs flying: Deciphering the organization and evolution of the neuronal network that controls wing flapping in birds.


Author(s):  
Bing Cai ◽  
Rong Yuan ◽  
Guo-Zhang Zhu ◽  
Wen-Feng Zhan ◽  
Cheng-En Luo ◽  
...  

Abstract Background Nasal filler placement is associated with a high risk of blindness. The arterial supply to the upper nose overlaying the nasal bones is poorly understood. Objectives The aim of this study was to visualize and analyze the deployment of the ophthalmic and facial angiosomes in the upper nose to help prevent blindness following nasal filler injections. Methods The arterial systems of 62 cadaveric heads were filled with lead oxide contrast agent, and computed tomography (CT) images were acquired and reconstructed in 3 dimensions. Results Twenty-six of the cadaveric noses examined demonstrated clear CT images of the facial and ophthalmic angiosomes in the upper nose. The Type 1 upper nose (15.4%) is supplied by 2 independent ophthalmic angiosomes that communicate indirectly through a choke anastomosis. The Type 2 upper nose (38.5%) is supplied by 2 ophthalmic angiosomes with a true anastomosis between them. The Type 3 upper nose (46.1%) is supplied by both ophthalmic and facial angiosomes with true anastomoses across the dorsal midline. These true anastomoses are mediated by the radix arcade in 46% of the noses and involve the dorsal nasal artery in 65% of the cases. The anastomoses all cross the upper dorsal midline and are directly linked to the ophthalmic angiosome. Conclusions The deployment and anastomosis of the facial and ophthalmic angiosomes in the upper nose fall into 3 major patterns. About 85% of the noses have true anastomotic arteries that cross the upper dorsal midline and are directly linked to the ophthalmic circulation. Dorsum filler injection poses a significant risk of blindness.


2021 ◽  
pp. 416-423
Author(s):  
YunHai Song ◽  
ZeYang Xia ◽  
ShanShan Qiu ◽  
PingPing Gao ◽  
Bo Yang ◽  
...  

<b><i>Objective:</i></b> This study aims to assess the impact of early diagnosis and surgery on children with congenital dermal sinus, investigate the relationship between MRI findings and extent of surgical exploration, and summarize our clinical experience with the surgical management in cases with central nervous system (CNS) infection. <b><i>Methods:</i></b> The skin features, preoperative MRI images, intraoperative findings, postoperative pathological characteristics, and prognoses of 56 children with congenital dermal sinus were analyzed retrospectively. <b><i>Results:</i></b> All the children had a pinpoint ostium in the skin, and 52 out of the 56 children (92.9%) had intraspinal dermoid cysts or epidermoid cysts. Before surgery, MRI did not show intraspinal lesions in 13 children, and surgery revealed intradural lesions in 9 of these children (69.2%). Among 46 children without CNS infection, 16 children had neurological impairment before surgery. After surgery, recovery was complete in 36 children, partial in 9 children, and absent in 3 children. All children with CNS infection had neurological impairment before surgery. After surgery, the condition improved in 8 children and exacerbated in 2 children. Children without CNS infection had statistically significantly better prognosis than children with CNS infection (<i>p</i> = 0.03). <b><i>Conclusion:</i></b> A pinpoint ostium in the dorsal midline is the characteristic feature of congenital dermal sinus. In cases without intraspinal lesions on MRI, the spinal canal should be explored intraoperatively to ensure complete removal of the lesion and prevent recurrences. In cases without CNS infection, early diagnosis and timely surgery are beneficial to the recovery of nerve function.


2021 ◽  
Vol 19 (2) ◽  
Author(s):  
Marcelo R. S. Melo ◽  
Bárbara B. Bouquerel ◽  
Flávia T. Masumoto ◽  
Rayane S. França ◽  
André L. Netto-Ferreira

Abstract A new species of Characidium is described from the tributaries of the rio Tocantinzinho, rio Tocantins basin, located in the southern portion of the Chapada dos Veadeiros, at about 1,200 meters of elevation, Goiás, Brazil. The new species can be diagnosed by an unusual combination of two apomorphic features present in distinct clades of Characidium, the presence of a scaleless isthmus in allied to with a single row of dentary teeth. Additionally, the new species has a unique color pattern of inconspicuous vertical bars disconnected from the dorsal midline, forming seven to nine square blotches along body sides, and the presence of a dark saddle-shaped mark at the dorsal-fin base. Osteologically, it can be diagnosed by having the first and second anal-fin proximal radials fused and contacting the third hemal spine, which is branched. The new species also has a peculiar, unusual variation of fin-ray counts among its congeners.


2020 ◽  
Vol 14 (6) ◽  
pp. 790-800
Author(s):  
Ju-Eun Kim ◽  
Dae-Jung Choi ◽  
Eugene J. Park

Study Design: Here we perform a retrospective analysis regarding an incidental dural tear (IDT) during biportal endoscopic spinal surgery (BESS).Purpose: This study investigates the causes of IDT specifically related to technical procedures of BESS with the aim of lowering its risk during training.Overview of Literature: The incidence of dural tear is reported 0.5%–18% in open spinal surgery and 1.7%–4.3% during endoscopic spinal surgery. Because conversion to open surgery for direct repair could become necessary during endoscopic spinal surgery, prevention of this complication is essential.Methods: We have retrospectively studied IDTs by four surgeons during 1 or 2 years after starting BESS for lumbar degenerative diseases and analyzed the locations, sizes, and specific endoscopic conditions specific to each.Results: Twenty-five cases (1.6%) of IDTs among 1,551 cases of BESS occurred; 13 cases (52%) of these were within the first 6 months. The locations were dorsal midline in 12 cases, ipsilateral side in 11 cases, and contralateral side in two cases. The tear sizes were <10 mm in 20 cases and ≥10 mm in five cases. IDT commonly occurred due to injury of central dural folding during flavectomy under turbid surgical fields due to small bleeds under water. Twenty cases with IDTs of <10 mm were treated well with the patch technique. Among five cases of ≥10 mm, three underwent open repair within a few days, and two of these which failed to conservative management required a delayed revision operation due to pseudomeningocele. No cases progressed to surgical site infection or infectious spondylitis.Conclusions: IDTs of <10 mm can be successfully treated with the patch technique. To prevent IDT during the early learning period, maintaining clear visibility by securing fluent saline outflow and meticulous hemostasis of small bleeding from exposed cancellous bone and epidural vessels is essential with caution not to injure the central dural folding during midline flavectomy.


PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0239357
Author(s):  
Junior J. West ◽  
Tony J. C. Harris

Cytohesin Arf-GEFs promote actin polymerization and protrusions of cultured cells, whereas the Drosophila cytohesin, Steppke, antagonizes actomyosin networks in several developmental contexts. To reconcile these findings, we analyzed epidermal leading edge actin networks during Drosophila embryo dorsal closure. Here, Steppke is required for F-actin of the actomyosin cable and for actin-based protrusions. steppke mutant defects in the leading edge actin networks are associated with improper sealing of the dorsal midline, but are distinguishable from effects of myosin mis-regulation. Steppke localizes to leading edge cell-cell junctions with accumulations of the F-actin regulator Enabled emanating from either side. Enabled requires Steppke for full leading edge recruitment, and genetic interaction shows the proteins cooperate for dorsal closure. Inversely, Steppke over-expression induces ectopic, actin-rich, lamellar cell protrusions, an effect dependent on the Arf-GEF activity and PH domain of Steppke, but independent of Steppke recruitment to myosin-rich AJs via its coiled-coil domain. Thus, Steppke promotes actin polymerization and cell protrusions, effects that occur in conjunction with Steppke’s previously reported regulation of myosin contractility during dorsal closure.


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