1. Articles in category: Developmental Biology

    193-216 of 252 « 1 2 ... 6 7 8 9 10 11 »
    1. Feature Of The Week 4/10/11: Dr. Kirill Larin Narrates a Presentation on OCT Imaging of In Utero Embryonic Development

      Feature Of The Week 4/10/11: Dr. Kirill Larin Narrates a Presentation on OCT Imaging of In Utero Embryonic Development
      Feature Of The Week 4/10/11: Dr. Kirill Larin narrates a presentation of execptional work from researchers at the Baylor College of Medicine and University of Houston on the use of Optical Coherence Tomography for high resolution imaging of mouse development in utero.   Understanding of the genetic basis of human birth defects heavily relies on analysis of mouse embryos. The success of these efforts depends on the ability to visualize and analyze phenotypic outcomes of genetic manipulations and pharmacological treatments.  A number of in vivo imaging methods have been developed to study mouse embryonic development, such as high-frequency ultrasound ...
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    2. Live Imaging of Mouse Embryos

      Live Imaging of Mouse Embryos
      The development of the mouse embryo is a dynamic process that requires the spatial and temporal coordination of multiple cell types as they migrate, proliferate, undergo apoptosis, and differentiate to form complex structures. However, the confined nature of embryos as they develop in utero limits our ability to observe these morphogenetic events in vivo. Previous work has used fixed samples and histological methods such as immunofluorescence or in situ hybridization to address expression or localization of a gene of interest within a developmental time line. However, such methods do not allow us to follow the complex, dynamic movements of individual ...
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    3. Optical coherence tomography for high-resolution imaging of mouse development in utero

      Optical coherence tomography for high-resolution imaging of mouse development in utero
      Although the mouse is a superior model to study mammalian embryonic development, high-resolution live dynamic visualization of mouse embryos remain a technical challenge. We present optical coherence tomography as a novel methodology for live imaging of mouse embryos through the uterine wall thereby allowing for time lapse analysis of developmental processes and direct phenotypic analysis of developing embryos. We assessed the capability of the proposed methodology to visualize structures of the living embryo from embryonic stages 12.5 to 18.5 days postcoitus. Repetitive in utero embryonic imaging is demonstrated. Our work opens the door for a wide range of ...
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    4. Function and form in the developing cardiovascular system

      Function and form in the developing cardiovascular system

      Function of the developing heart is dictated by changes in its morphology. For simplicity, we distinguish four stages with different contraction mechanics and conduction parameters. Straight or looped tubular hearts, similar to those of invertebrates such as Drosophila or Ciona, operate as suction pumps and are characterized by a caudally localized pacemaker and slow, peristaltoid conduction and contraction. There is a complete occlusion of the lumen during systole. When the atrial and ventricular chambers appear, the preseptation heart is in many functional aspects similar to the adult heart, but the same function is achieved by different means. There are parallels ...

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    5. Bioptigen OCT Captures the Hyper-Reflective Cone Mosaic in Zebrafish Retina

      Bioptigen OCT Captures the Hyper-Reflective Cone Mosaic in Zebrafish Retina
      Bioptigen Press Release: Bioptigen demonstrates the application of a commercial SDOCT system to imaging the whole eye of the adult zebrafish. Images of the cornea, iris, lens, vitreous, retina, and cone mosaic are shown in the attached presentation. The Bioptigen SDOIS system is implemented with the handheld scanner mounted vertically, pointing down. First, an alert zebrafish is placed in a cuvette with anesthesia and ceases to move within 30 seconds. The cuvette is placed on a 5-axis stereotactic mount (Bioptigen ZAS accessory) and positioned to co-align the nodal point of the raster scan, the geometrical nodal point of the stage ...
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      Mentions: Bioptigen
    6. Non-invasive imaging and monitoring of rodent retina using simultaneous dual-band optical coherence tomography

      Non-invasive imaging and monitoring of rodent retina using simultaneous dual-band optical coherence tomography

      Spectral domain dual-band optical coherence tomography for simultaneous imaging of rodent retina in the 0.8 μm and 1.3 μm wavelength region and non-invasive monitoring of the posterior eye microstructure in the field of retinal degeneration research is demonstrated. The system is illuminated by a supercontinuum laser source and allows three-dimensional imaging with high axial resolution better than 3.8 μm and 5.3 μm in tissue at 800 nm and 1250 nm, respectively, for precise retinal thickness measurements. A fan-shaped scanning pattern with the pivot point close to the eye's pupil and a contact lens are applied ...

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    7. SMAD signaling drives heart and muscle dysfunction in a Drosophila model of muscular dystrophy

      SMAD signaling drives heart and muscle dysfunction in a Drosophila model of muscular dystrophy
      Loss-of-function mutations in the genes encoding dystrophin and the associated membrane proteins, the sarcoglycans, produce muscular dystrophy and cardiomyopathy. The dystrophin complex provides stability to the plasma membrane of striated muscle during muscle contraction. Increased SMAD signaling due to activation of the transforming growth factor-β (TGFβ) pathway has been described in muscular dystrophy; however, it is not known whether this canonical TGFβ signaling is pathogenic in the muscle itself. Drosophila deleted for the γ/δ-sarcoglycan gene (Sgcd) develop progressive muscle and heart dysfunction and serve as a model for the human disorder. We used dad-lacZ flies to demonstrate the signature ...
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    8. Optical Coherence Tomography Imaging of Early Quail Embryos

      Optical Coherence Tomography Imaging of Early Quail Embryos
      Congenital heart defects (CHDs) affect thousands of newborns each year in the United States. Recent research using animal model systems indicates that the abnormal function of the early tubular heart precedes structural defects such as septal defects. Optical coherence tomography (OCT) is an imaging modality that can provide high spatial and temporal resolution to study both the structure and the function of the tubular heart. With technical advances in OCT imaging speed, especially with frequency domain OCT and image-based retrospective gating, it is now possible to image a beating avian embryonic heart in three dimensions under physiological conditions and follow ...
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    9. High-Speed Optical Coherence Tomography Imaging of the Beating Avian Embryonic Heart

      High-Speed Optical Coherence Tomography Imaging of the Beating Avian Embryonic Heart
      Congenital heart defects (CHDs) affect thousands of newborns each year in the United States. Recent research using animal model systems indicates that the abnormal function of the early tubular heart precedes structural defects such as septal defects. Optical coherence tomography (OCT) is an imaging modality that can provide high spatial and temporal resolution to study both the structure and the function of the tubular heart. With technical advances in OCT imaging speed, especially with frequency domain OCT and image-based retrospective gating, it is now possible to image a beating avian embryonic heart in three dimensions under physiological conditions and follow ...
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    10. Speckle variance OCT imaging of the vasculature in live mammalian embryos

      Speckle variance OCT imaging of the vasculature in live mammalian embryos

      Live imaging of normal and abnormal vascular development in mammalian embryos is important tool in embryonic research, which can potentially contribute to understanding, prevention and treatment of cardiovascular birth defects. Here, we used speckle variance analysis of swept source optical coherence tomography (OCT) data sets acquired from live mouse embryos to reconstruct the 3-D structure of the embryonic vasculature. Both Doppler OCT and speckle variance algorithms were used to reconstruct the vascular structure. The results demonstrates that speckle variance imaging provides more accurate representation of the vascular structure, as it is not sensitive to the blood flow direction, while the ...

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    11. Physiological homology between Drosophila melanogaster and vertebrate cardiovascular systems

      Physiological homology between Drosophila melanogaster and vertebrate cardiovascular systems
      The physiology of the Drosophila melanogaster cardiovascular system remains poorly characterized compared with its vertebrate counterparts. Basic measures of physiological performance remain unknown. It also is unclear whether subtle physiological defects observed in the human cardiovascular system can be reproduced in D. melanogaster. Here we characterize the cardiovascular physiology of D. melanogaster in its pre-pupal stage by using high-speed dye angiography and optical coherence tomography. The heart has vigorous pulsatile contractions that drive intracardiac, aortic and extracellular-extravascular hemolymph flow. Several physiological measures, including weight-adjusted cardiac output, body-length-adjusted aortic velocities and intracardiac shear forces, are similar to those in the closed ...
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    12. Arrhythmia Caused by a Drosophila Tropomyosin Mutation Is Revealed Using a Novel Optical Coherence Tomography Instrument

      Arrhythmia Caused by a Drosophila Tropomyosin Mutation Is Revealed Using a Novel Optical Coherence Tomography Instrument
      Background Dilated cardiomyopathy (DCM) is a severe cardiac condition that causes high mortality. Many genes have been confirmed to be involved in this disease. An ideal system with which to uncover disease mechanisms would be one that can measure the changes in a wide range of cardiac activities associated with mutations in specific, diversely functional cardiac genes. Such a system needs a genetically manipulable model organism that allows in vivo measurement of cardiac phenotypes and a detecting instrument capable of recording multiple phenotype parameters. Methodology and Principal Findings With a simple heart, a transparent body surface at larval stages and ...
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    13. Measuring hemodynamics in the developing heart tube with four-dimensional gated Doppler optical coherence tomography

      Measuring hemodynamics in the developing heart tube with four-dimensional gated Doppler optical coherence tomography

      Hemodynamics is thought to play a major role in heart development, yet tools to quantitatively assess hemodynamics in the embryo are sorely lacking. The especially challenging analysis of hemodynamics in the early embryo requires new technology. Small changes in blood flow could indicate when anomalies are initiated even before structural changes can be detected. Furthermore, small changes in the early embryo that affect blood flow could lead to profound abnormalities at later stages. We present a demonstration of 4-D Doppler optical coherence tomography (OCT) imaging of structure and flow, and present several new hemodynamic measurements on embryonic avian hearts at ...

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    14. Heart wall velocimetry and exogenous contrast-based cardiac flow imaging in Drosophila melanogaster using Doppler optical coherence tomography

      Heart wall velocimetry and exogenous contrast-based cardiac flow imaging in Drosophila melanogaster using Doppler optical coherence tomography
      Drosophila melanogaster (fruit fly) is a central organism in biology and is becoming increasingly important in the cardiovascular sciences. Prior work in optical imaging of the D. melanogaster heart has focused on static and dynamic structural anatomy. In the study, it is demonstrated that Doppler optical coherence tomography can quantify dynamic heart wall velocity and hemolymph flow in adult D. melanogaster. Since hemolymph is optically transparent, a novel exogenous contrast technique is demonstrated to increase the backscatter-based intracardiac Doppler flow signal. The results presented here open up new possibilities for functional cardiovascular phenotyping of normal and mutant D. melanogaster.
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    15. Mechanics of head fold formation: investigating tissue-level forces forces during early development

      Mechanics of head fold formation: investigating tissue-level forces forces during early development
      During its earliest stages, the avian embryo is approximately planar. Through a complex series of folds, this flat geometry is transformed into the intricate three-dimensional structure of the developing organism. Formation of the head fold (HF) is the first step in this cascading sequence of out-of-plane tissue folds. The HF establishes the anterior extent of the embryo and initiates heart, foregut and brain development. Here, we use a combination of computational modeling and experiments to determine the physical forces that drive HF formation. Using chick embryos cultured ex ovo, we measured: (1) changes in tissue morphology in living embryos using ...
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    16. Imaging modalities to assess structural birth defects in mutant mouse models

      Imaging modalities to assess structural birth defects in mutant mouse models
      Assessment of structural birth defects (SBDs) in animal models usually entails conducting detailed necropsy for anatomical defects followed by histological analysis for tissue defects. Recent advances in new imaging technologies have provided the means for rapid phenotyping of SBDs, such as using ultra-high frequency ultrasound biomicroscopy, optical coherence tomography, micro-CT, and micro-MRI. These imaging modalities allow the detailed assessment of organ/tissue structure, and with ultrasound biomicroscopy, structure and function of the cardiovascular system also can be assessed noninvasively, allowing the longitudinal tracking of the fetus in utero. In this review, we briefly discuss the application of these state-of-the-art imaging ...
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    17. Measurement of absolute blood flow velocity in outflow tract of HH18 chicken embryo based on 4D reconstruction using spectral domain optical coherence tomography

      Measurement of absolute blood flow velocity in outflow tract of HH18 chicken embryo based on 4D reconstruction using spectral domain optical coherence tomography

      The measurement of blood-plasma absolute velocity distributions with high spatial and temporal resolution in vivo is important for the investigation of embryonic heart at its early stage of development. We introduce a novel method to measure absolute blood flow velocity based on high speed spectral domain optical coherence tomography (OCT) and apply it to measure velocities across the heart outflow tract (OFT) of a chicken embryo (stage HH18). First, we use the OCT system to acquire 4D 
[(x,y,z) + t] images of the OFT in vivo. Second, we reconstruct the 4D microstructural images and obtain the orientation of the ...

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    18. Optical coherence tomography as approach for the minimal invasive localization of the germinal disc in ovo before chicken sexing

      Optical coherence tomography as approach for the minimal invasive localization of the germinal disc in ovo before chicken sexing
      In most industrial states a huge amount of newly hatched male layer chickens are usually killed immediately after hatching by maceration or gassing. The reason for killing most of the male chickens of egg producing races is their slow growth rate compared to races specialized on meat production. When the egg has been laid, the egg contains already a small disc of cells on the surface of the yolk known as the blastoderm. This region is about 4 - 5 mm in diameter and contains the information whether the chick becomes male or female and hence allows sexing of the chicks ...
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    19. The Embryonic Heart: Imaging Life as it Happens - University of Houston Professor Captures Video of Heart Before it Begins to Beat (Video Snippet)

      The Embryonic Heart: Imaging Life as it Happens - University of Houston Professor Captures Video of Heart Before it Begins to Beat (Video Snippet)
      Imagine being able to image life as it happens by capturing video of the embryonic heart before it begins beating. A professor at the University of Houston, in collaboration with scientists at Baylor College of Medicine, is doing just that. Kirill Larin, assistant professor of biomedical engineering in the Cullen College of Engineering at UH, and his colleagues in the Texas Medical Center are documenting the formation of the mammalian heart through a high-resolution, non-invasive imaging device, providing perhaps the best live imagery taken of the vital organ. “Everything we know about early development of the heart and formation of ...
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    20. Gene Deletion Screen for Cardiomyopathy in Adult Drosophila Identifies a New Notch Ligand

      Gene Deletion Screen for Cardiomyopathy in Adult Drosophila Identifies a New Notch Ligand
      Rationale: Drosophila has been recognized as a model to study human cardiac diseases. Objective: Despite these findings, and the wealth of tools that are available to the fly community, forward genetic screens for adult heart phenotypes have been rarely performed because of the difficulty in accurately measuring cardiac function in adult Drosophila. Methods and Results: Using optical coherence tomography to obtain real-time analysis of cardiac function in awake Drosophila, we performed a genomic deficiency screen in adult flies. Based on multiple complementary approaches, we identified CG31665 as a novel gene causing dilated cardiomyopathy. CG31665, which we name weary (wry), has ...
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    21. Imaging of mouse embryonic eye development using optical coherence tomography

      Imaging of mouse embryonic eye development using optical coherence tomography
      Congenital abnormalities are often caused by genetic disorders which alter the normal development of the eye. Embryonic eye imaging in mouse model is important for understanding of normal and abnormal eye development and can contribute to prevention and treatment of eye defects in humans. In this study, we used Swept Source Optical Coherence Tomography (SS-OCT) to image eye structure in mouse embryos at 12.5 to 17.5 days post coitus (dpc). The imaging depth of the OCT allowed us to visualize the whole eye globe at these stages. Different ocular tissues including lens, cornea, eyelids, and hyaloid vasculature were ...
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    22. Focusing light through living tissue

      Focusing light through living tissue
      Tissues such as skin, fat or cuticle are non-transparent because inhomogeneities in the tissue scatter light. We demonstrate experimentally that light can be focused through turbid layers of living tissue, in spite of scattering. Our method is based on the fact that coherent light forms an interference pattern, even after hundreds of scattering events. By spatially shaping the wavefront of the incident laser beam, this interference pattern was modified to make the scattered light converge to a focus. In contrast to earlier experiments, where light was focused through solid objects, we focused light through living pupae of Drosophila melanogaster. We ...
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    23. Minimal invasive localization of the germinal disc in ovo for subsequent chicken sexing using optical coherence tomography

      Minimal invasive localization of the germinal disc in ovo for subsequent chicken sexing using optical coherence tomography

      Reason for using optical coherence tomography (OCT) to locate the germinal disc is the questionable and ethically alarming killing of male layer chickens because for the layer line only the females are necessary. To avoid this and to protect the animal rights, the sex of the fertilized chicken egg has to be determined as early as possible in the unincubated state. Because the information whether the chick becomes male or female can be found in the germinal disc an accurate localization for sexing is essential. The germinal disc is located somewhere on top of the yolk and has a diameter ...

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    24. Gabor-based fusion technique for Optical Coherence Microscopy

      Gabor-based fusion technique for Optical Coherence Microscopy
      We recently reported on an Optical Coherence Microscopy technique, whose innovation intrinsically builds on a recently reported - 2 μm invariant lateral resolution by design throughout a 2 mm cubic full-field of view - liquid-lens-based dynamic focusing optical probe [Murali et al.,Optics Letters 34, 145-147, 2009]. We shall report in this paper on the image acquisition enabled by this optical probe when combined with an automatic data fusion method developed and described here to produce an in-focus high resolution image throughout the imaging depth of the sample. An African frog tadpole (Xenopus laevis) was imaged with the novel probe and the ...
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