1. Articles in category: Developmental Biology

    49-72 of 256 « 1 2 3 4 5 6 ... 9 10 11 »
    1. Four-dimensional live imaging of hemodynamics in mammalian embryonic heart with Doppler optical coherence tomography

      Four-dimensional live imaging of hemodynamics in mammalian embryonic heart with Doppler optical coherence tomography

      Four-dimensional live hemodynamic imaging of the mouse embryonic heart at embryonic day 9.0 using Doppler optical coherence tomography, showing directional blood flows in the sinus venosus, primitive atrium, atrioventricular region and vitelline vein. Hemodynamic analysis of the mouse embryonic heart is essential for understanding the functional aspects of early cardiogenesis and advancing the research in congenital heart defects. However, high-resolution imaging of cardiac hemodynamics in mammalian models remains challenging, primarily due to the dynamic nature and deep location of the embryonic heart. Here we report four-dimensional micro-scale imaging of blood flow in the early mouse embryonic heart, enabling time-resolved ...

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    2. Feature of the Week 03/20/2016: Closed Loop Tracked Doppler OCT Based Heart Monitor for the Drosophila Melanogaster Larvae

      Feature of the Week 03/20/2016: Closed Loop Tracked Doppler OCT Based Heart Monitor for the Drosophila Melanogaster Larvae

      A fruit fly larva (top) was continuously tracked for continuous remote monitoring. A heartbeat trace of freely moving larva (bottom) was obtained by a low coherence interferometry based doppler sensing technique. This paper presents a novel instrument for biosciences, useful for studies of moving embryos. A dual sequential imaging/measurement channel is assembled via a closed-loop tracking architecture. The dual channel system can operate in two regimes: (i) single-point Doppler signal monitoring or (ii) fast 3-D swept source OCT imaging. The system is demonstrated for characterizing cardiac dynamics in Drosophila melanogaster larva. Closed loop tracking enables long term in vivo ...

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    3. Optical coherence tomography for detection of compound action potential in Xenopus Laevis sciatic nerve

      Optical coherence tomography for detection of compound action potential in Xenopus Laevis sciatic nerve

      Due to optical coherence tomography (OCT) high spatial and temporal resolution, this technique could be used to observe the quick changes in the refractive index that accompany action potential. In this study we explore the use of time domain Optical Coherence Tomography (TD-OCT) for real time action potential detection in ex vivo Xenopus Laevis sciatic nerve. TD-OCT is the easiest and less expensive OCT technique and, if successful in detecting real time action potential, it could be used for low cost monitoring devices. A theoretical investigation into the order of magnitude of the signals detected by a TD-OCT setup is ...

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    4. Optical coherence tomography imaging of colonic crypts in a mouse model of colorectal cancer

      Optical coherence tomography imaging of colonic crypts in a mouse model of colorectal cancer

      Aberrant crypt foci (ACF) are abnormal epithelial lesions that precede development of colonic polyps. As the earliest morphological change in the development of colorectal cancer, ACF is a highly studied phenomenon. The most common method of imaging ACF is chromoendoscopy using methylene blue as a contrast agent. Narrow- band imaging is a contrast-agent-free modality for imaging the colonic crypts. Optical coherence tomography (OCT) is an attractive alternative to chromoendoscopy and narrow-band imaging because it can resolve the crypt structure at sufficiently high sampling while simultaneously providing depth-resolved data. We imaged in vivo the distal 15 mm of colon in the ...

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    5. Imaging of the stroke-related changes in the vascular system of the mouse brain with the use of extended focus Optical Coherence Microscopy

      Imaging of the stroke-related changes in the vascular system of the mouse brain with the use of extended focus Optical Coherence Microscopy

      We used Optical Coherence Microscopy (OCM) to monitor structural and functional changes due to ischemic stroke in small animals brains in vivo. To obtain lateral resolution of 2.2 μm over the range of 600 μm we used extended focus configuration of OCM instrument involving Bessel beam. It provided access to detailed 3D information about the changes in brain vascular system up to the level of capillaries across I and II/III layers of neocortex. We used photothrombotic stroke model involving photoactive application of rose bengal to assure minimal invasiveness of the procedure and precise localization of the clot distribution ...

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    6. Measurement of strain and strain rate in embryonic chick heart using spectral domain optical coherence tomography

      Measurement of strain and strain rate in embryonic chick heart using spectral domain optical coherence tomography

      It is important to measure embryonic heart myocardial wall strain and strain rate for understanding the mechanisms of embryonic heart development. Optical coherence tomography (OCT) can provide depth resolved images with high spatial and temporal resolution, which makes it have the potential to reveal the complex myocardial activity in the early stage embryonic heart. We develop a novel method to measure strain in embryonic chick heart based on spectral domain OCT images and subsequent image processing. We perform 4D(x,y,z,t) scanning on the outflow tract (OFT) of chick embryonic hearts in HH18 stage (~3 days of incubation ...

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    7. Blood flowing state analysis in outflow tract of chick embryonic heart based on spectral domain optical coherence tomography

      Blood flowing state analysis in outflow tract of chick embryonic heart based on spectral domain optical coherence tomography

      The cardiac development is a complicated process affected by genetic and environmental factors. Wall shear stress (WSS) and periodic stress (WPS) are the components which have been proved to influence the morphogenesis during early stages of cardiac development. The vessel wall will be deformed by the blood pressure and produce natural elastic force acting on the blood. Because blood flowing in different flow state and show different characteristics of fluid, which influence the calculation of WSS and WPS directly, it is necessary to study the blood flow state. In this paper, we introduce a method to quantify the blood flowing ...

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    8. Label-free imaging of developing vasculature in zebrafish with phase variance optical coherence microscopy

      Label-free imaging of developing vasculature in zebrafish with phase variance optical coherence microscopy

      A phase variance optical coherence microscope (pvOCM) has been created to visualize blood flow in the vasculature of zebrafish embryos, without using exogenous labels. The pvOCM imaging system has axial and lateral resolutions of 2 μm in tissue, and imaging depth of more than 100 μm. Imaging of 2–5 days post-fertilization zebrafish embryos identified the detailed structures of somites, spinal cord, gut and notochord based on intensity contrast. Visualization of the blood flow in the aorta, veins and intersegmental vessels was achieved with phase variance contrast. The pvOCM vasculature images were confirmed with corresponding fluorescence microscopy of a zebrafish ...

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    9. Comparison of rotational imaging optical coherence tomography and selective plane illumination microscopy for embryonic study

      Comparison of rotational imaging optical coherence tomography and selective plane illumination microscopy for embryonic study

      The mouse is a common model for studying developmental diseases. Different optical techniques have been developed to investigate mouse embryos, but each has its own set of limitations and restrictions. In this study, we imaged the same E9.5 mouse embryo with rotational imaging Optical Coherence Tomography (RI-OCT) and Selective Plane Illumination Microscopy (SPIM), and compared the two techniques. Results demonstrate that both methods can provide images with micrometer-scale spatial resolution. The RI-OCT technique was developed to increase imaging depth of OCT by performing traditional OCT imaging at multiple sides and co-registering the images. In SPIM, optical sectioning is achieved ...

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    10. Live 4D optical coherence tomography for early embryonic mouse cardiac phenotyping

      Live 4D optical coherence tomography for early embryonic mouse cardiac phenotyping

      Studying embryonic mouse development is important for our understanding of normal human embryogenesis and the underlying causes of congenital defects. Our research focuses on imaging early development in the mouse embryo to specifically understand cardiovascular development using optical coherence tomography (OCT). We have previously developed imaging approaches that combine static embryo culture, OCT imaging and advanced image processing to visualize the whole live mouse embryos and obtain 4D (3D+time) cardiodynamic datasets with cellular resolution. Here, we present the study of using 4D OCT for dynamic imaging of early embryonic heart in live mouse embryos to assess mutant cardiac phenotypes ...

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    11. Three-dimensional imaging of the developing mouse female reproductive organs with optical coherence tomography

      Three-dimensional imaging of the developing mouse female reproductive organs with optical coherence tomography

      Infertility is a known major health concern and is estimated to impact ~15% of couples in the U.S. The majority of failed pregnancies occur before or during implantation of the fertilized embryo into the uterus. Understanding the mechanisms regulating development by studying mouse reproductive organs could significantly contribute to an improved understanding of normal development of reproductive organs and developmental causes of infertility in humans. Towards this goal, we report a three-dimensional (3D) imaging study of the developing mouse reproductive organs (ovary, oviduct, and uterus) using optical coherence tomography (OCT). In our study, OCT was used for 3D imaging ...

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    12. Functional optical coherence tomography for high-resolution mapping of cilia beat frequency in the mouse oviduct in vivo

      Functional optical coherence tomography for high-resolution mapping of cilia beat frequency in the mouse oviduct in vivo

      Since mouse is a superior model for genetic analysis of human disorders, reproductive studies in mice have significant implications on further understanding of fertility and infertility in humans. Fertilized oocytes are transported through the reproductive tract by motile cilia lining the lumen of the oviduct as well as by oviduct contractions. While the role of cilia is well recognized, ciliary dynamics in the oviduct is not well understood, largely owing to the lack of live imaging approaches. Here, we report in vivo micro-scale mapping of cilia and cilia beat frequency (CBF) in the mouse oviduct using optical coherence tomography (OCT ...

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    13. Rotational imaging optical coherence tomography for full-body mouse embryonic imaging

      Rotational imaging optical coherence tomography for full-body mouse embryonic imaging

      Optical coherence tomography (OCT) has been widely used to study mammalian embryonic development with the advantages of high spatial and temporal resolutions and without the need for any contrast enhancement probes. However, the limited imaging depth of traditional OCT might prohibit visualization of the full embryonic body. To overcome this limitation, we have developed a new methodology to enhance the imaging range of OCT in embryonic day (E) 9.5 and 10.5 mouse embryos using rotational imaging. Rotational imaging OCT (RI-OCT) enables full-body imaging of mouse embryos by performing multiangle imaging. A series of postprocessing procedures was performed on ...

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    14. Classifying murine glomerulonephritis using optical coherence tomography and optical coherence elastography

      Classifying murine glomerulonephritis using optical coherence tomography and optical coherence elastography

      Elastic-wave propagation in mouse healthy and nephritic kidneys. Acute glomerulonephritis caused by antiglomerular basement membrane marked by high mortality. The primary reason for this is delayed diagnosis via blood examination, urine analysis, tissue biopsy, or ultrasound and X-ray computed tomography imaging. Blood, urine, and tissue-based diagnoses can be time consuming, while ultrasound and CT imaging have relatively low spatial resolution, with reduced sensitivity. Optical coherence tomography is a noninvasive and high-resolution imaging technique that provides superior spatial resolution (micrometer scale) as compared to ultrasound and CT. Changes in tissue properties can be detected based on the optical metrics analyzed from ...

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    15. University of Houston Receives NIH Grant for Optical Coherence Tomography to Study Effect of Poly-Drug Exposure of Fetal Brain Development

      University of Houston Receives NIH Grant for Optical Coherence Tomography to Study Effect of Poly-Drug Exposure of Fetal Brain Development

      University of Houston Receives a 2016 NIH Grant for $424,849 for Optical Coherence Tomography to Study Effect of Poly-Drug Exposure of Fetal Brain Development. The principal investigator is Kirill Larin. The program began in 2016 and ends in 2020. Below is a summary of the proposed work. The overall objective of this study is to develop an optical coherence tomography (OCT) based high- resolution mouse embryonic brain imaging and analysis approach, and to use this method in correlation with molecular analysis to understand the interplay between ethanol (EtOH) and nicotine (NIC) effects on embryonic brain development. Maternal exposures to ...

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    16. In vivo three-dimensional characterization of the adult zebrafish brain using a 1325 nm spectral-domain optical coherence tomography system with the 27 frame/s video rate

      In vivo three-dimensional characterization of the adult zebrafish brain using a 1325 nm spectral-domain optical coherence tomography system with the 27 frame/s video rate

      In this study, a spectral-domain optical coherence tomography (SD-OCT) system was used for noninvasive imaging of the adult zebrafish brain. Based on a 1325 nm light source and two high-speed galvo mirrors, our SD-OCT system can offer a large field of view of brain morphology with high resolution (12 μm axial and 13 μm lateral) at video rate (27 frame/s). In vivo imaging of both the control and injured brain was performed using adult zebrafish model. The recovered results revealed that olfactory bulb, optic commissure, telencephalon, tectum opticum, cerebellum, medulla, preglomerular complex and posterior tuberculum could be clearly identified ...

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    17. In vivo assessment of wall strain in embryonic chick heart by spectral domain optical coherence tomography

      In vivo assessment of wall strain in embryonic chick heart by spectral domain optical coherence tomography

      The ability to measure in vivo wall strain in embryonic hearts is important for fully understanding the mechanisms of cardiac development. Optical coherence tomography (OCT) is a powerful tool for the three-dimensional imaging of complex myocardial activities in early-stage embryonic hearts with high spatial and temporal resolutions. We describe a method to analyze periodic deformations of myocardial walls and evaluate in vivo myocardial wall strains with a high-speed spectral domain OCT system. We perform four-dimensional scanning on the outflow tract (OFT) of chick embryonic hearts and determine a special cross-section in which the OFT can be approximated as an annulus ...

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    18. Laminar microvascular transit time distribution in the mouse somatosensory cortex revealed by Dynamic Contrast Optical Coherence Tomography

      Laminar microvascular transit time distribution in the mouse somatosensory cortex revealed by Dynamic Contrast Optical Coherence Tomography

      The transit time distribution of blood through the cerebral microvasculature both constrains oxygen delivery and governs the kinetics of neuroimaging signals such as blood-oxygen-level-dependent functional Magnetic Resonance Imaging (BOLD fMRI). However, in spite of its importance, capillary transit time distribution has been challenging to quantify comprehensively and efficiently at the microscopic level. Here, we introduce a method, called Dynamic Contrast Optical Coherence Tomography (DyC-OCT), based on dynamic cross-sectional OCT imaging of an intravascular tracer as it passes through the field-of-view. Quantitative transit time metrics are derived from temporal analysis of the dynamic scattering signal, closely related to tracer concentration. Since ...

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    19. Blood flow through the embryonic heart outflow tract during cardiac looping in HH13–HH18 chicken embryos

      Blood flow through the embryonic heart outflow tract during cardiac looping in HH13–HH18 chicken embryos

      Blood flow is inherently linked to embryonic cardiac development, as haemodynamic forces exerted by flow stimulate mechanotransduction mechanisms that modulate cardiac growth and remodelling. This study evaluated blood flow in the embryonic heart outflow tract (OFT) during normal development at each stage between HH13 and HH18 in chicken embryos, in order to characterize changes in haemodynamic conditions during critical cardiac looping transformations. Two-dimensional optical coherence tomography was used to simultaneously acquire both structural and Doppler flow images, in order to extract blood flow velocity and structural information and estimate haemodynamic measures. From HH13 to HH18, peak blood flow rate increased ...

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    20. Direct four-dimensional structural and functional imaging of cardiovascular dynamics in mouse embryos with 1.5  MHz optical coherence tomography

      Direct four-dimensional structural and functional imaging of cardiovascular dynamics in mouse embryos with 1.5  MHz optical coherence tomography

      High-resolution three-dimensional (3D) imaging of cardiovascular dynamics in mouse embryos is greatly desired to study mammalian congenital cardiac defects. Here, we demonstrate direct four-dimensional (4D) imaging of the cardiovascular structure and function in live mouse embryos at a ∼ 43     Hz volume rate using an optical coherence tomography (OCT) system with a ∼ 1.5     MHz Fourier domain mode-locking swept laser source. Combining ultrafast OCT imaging with live mouse embryo culture protocols, 3D volumes of the embryo are directly and continuously acquired over time for a cardiodynamics analysis without the application of any synchronization algorithms. We present the time-resolved measurements of the ...

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    21. Optogenetic pacing in Drosophila melanogaster

      Optogenetic pacing in Drosophila melanogaster

      Electrical stimulation is currently the gold standard for cardiac pacing. However, it is invasive and nonspecific for cardiac tissues. We recently developed a noninvasive cardiac pacing technique using optogenetic tools, which are widely used in neuroscience. Optogenetic pacing of the heart provides high spatial and temporal precisions, is specific for cardiac tissues, avoids artifacts associated with electrical stimulation, and therefore promises to be a powerful tool in basic cardiac research. We demonstrated optogenetic control of heart rhythm in a well-established model organism, Drosophila melanogaster . We developed transgenic flies expressing a light-gated cation channel, channelrhodopsin-2 (ChR2), specifically in their hearts and ...

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    22. 4D subject-specific inverse modeling of the chick embryonic heart outflow tract hemodynamics

      4D subject-specific inverse modeling of the chick embryonic heart outflow tract hemodynamics

      Blood flow plays a critical role in regulating embryonic cardiac growth and development, with altered flow leading to congenital heart disease. Progress in the field, however, is hindered by a lack of quantification of hemodynamic conditions in the developing heart. In this study, we present a methodology to quantify blood flow dynamics in the embryonic heart using subject-specific computational fluid dynamics (CFD) models. While the methodology is general, we focused on a model of the chick embryonic heart outflow tract (OFT), which distally connects the heart to the arterial system, and is the region of origin of many congenital cardiac ...

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    23. A Circadian Clock Gene, Cry, Affects Heart Morphogenesis and Function in Drosophila as Revealed by Optical Coherence Microscopy

      A Circadian Clock Gene, Cry, Affects Heart Morphogenesis and Function in Drosophila as Revealed by Optical Coherence Microscopy

      Circadian rhythms are endogenous, entrainable oscillations of physical, mental and behavioural processes in response to local environmental cues such as daylight, which are present in the living beings, including humans. Circadian rhythms have been related to cardiovascular function and pathology. However, the role that circadian clock genes play in heart development and function in a whole animal in vivo are poorly understood. The Drosophila cryptochrome (dCry) is a circadian clock gene that encodes a major component of the circadian clock negative feedback loop. Compared to the embryonic stage, the relative expression levels of dCry showed a significant increase (>100-fold) in ...

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    24. Label-free characterization of vitrification-induced morphology changes in single-cell embryos with full-field optical coherence tomography

      Label-free characterization of vitrification-induced morphology changes in single-cell embryos with full-field optical coherence tomography

      Vitrification is an increasingly popular method of embryo cryopreservation that is used in assisted reproductive technology. Although vitrification has high post-thaw survival rates compared to other freezing techniques, its long-term effects on embryo development are still poorly understood. We demonstrate an application of full-field optical coherence tomography (FF-OCT) to visualize the effects of vitrification on live single-cell (2 pronuclear) mouse embryos without harmful labels. Using FF-OCT, we observed that vitrification causes a significant increase in the aggregation of structures within the embryo cytoplasm, consistent with reports in literature based on fluorescence techniques. We quantify the degree of aggregation with an ...

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    49-72 of 256 « 1 2 3 4 5 6 ... 9 10 11 »
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