1. Articles in category: Developmental Biology

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    1. Repeatability and Reproducibility of In Vivo Cone Density Measurements in the Adult Zebrafish Retina

      Repeatability and Reproducibility of In Vivo Cone Density Measurements in the Adult Zebrafish Retina

      Zebrafish ( Danio rerio ) are widely used as an experimental model for a wide range of retinal diseases. Previously, optical coherence tomography (OCT) was introduced for quantitative analysis of the zebrafish cone photoreceptor cell mosaic; however no data exists on the intersession reproducibility or intrasession repeatability of such measurements. We imaged 14 wild-type (WT) fish three times each, with 48 h between each time point. En face images of the UV cone mosaic were generated from the OCT volume scans at each time point. These images were then aligned and the overlapping area cropped for analysis. Using a semiautomated cone-counting algorithm ...

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    2. In Vivo Imaging of the Mouse Reproductive Organs, Embryo Transfer, and Oviduct Cilia Dynamics Using Optical Coherence Tomography

      In Vivo Imaging of the Mouse Reproductive Organs, Embryo Transfer, and Oviduct Cilia Dynamics Using Optical Coherence Tomography

      The oviduct (or fallopian tube) serves as the site where a number of major reproductive events occur for the start of a new life in mammals. Understanding the oviduct physiology is essential to uncover hidden mechanisms of the human reproduction and its disorders, yet the current analysis of the oviduct that is largely limited to in vitro imaging is a significant technical hurdle. To overcome this barrier, we have recently developed in vivo approaches based on optical coherence tomography for structural and functional imaging of the mouse oviduct. In this chapter, we describe the details of such live imaging methods ...

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    3. Using optical coherence tomography to detect disturbances in coronary microvascular in a model of fetal alcohol syndrome

      Using optical coherence tomography to detect disturbances in coronary microvascular in a model of fetal alcohol syndrome

      Congenital coronary anomalies can result in severe consequences such as arrhythmias and sudden death. However, the etiology of abnormal embryonic coronary microvasculature development is understudied. Using a novel contrast-agent-based optical coherence tomography (OCT) technique, scatter labeled imaging of microvasculature in excised tissue (SLIME), we compared diseased and normal embryonic quail coronary microvasculature in 3D. Congenital heart defects associated with fetal alcohol syndrome (FAS) were induced in a quail model by injecting 40 uL of 50% ethanol solution into eggs during gastrulation. These and saline-injected quail eggs were incubated until stage 36. SLIME contrast agent was perfused through the aortas of ...

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    4. Optical coherence computed tomography for quantitative 3D imaging of adult zebrafish

      Optical coherence computed tomography for quantitative 3D imaging of adult zebrafish

      Optical imaging in turbid media like biological tissue is limited by light scattering. We present optical coherence computed tomography (OCCT) as a novel optical imaging modality for ballistic 3D optical imaging of turbid media. In OCCT, coherence and confocal gated measurements from multiple lateral positions and angles are used to reconstruct quantitative 3D images of the optical attenuation and refractive index with tomographic reconstruction algorithms. OCCT allows for high resolution imaging in turbid media by strong suppression of scattered light using a combination of coherence and confocal gating. The time-of-flight information in the transmission measurements allows for quantitative reconstruction of ...

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    5. In vivo three-dimensional tracking of sperm behaviors in the mouse oviduct

      In vivo three-dimensional tracking of sperm behaviors in the mouse oviduct

      Mammalian sperm evolutionarily acquired complex mechanisms regulating their behaviors, which are thought to be critical in navigating through the female reproductive tract toward fertilization. However, all current knowledge of this process is largely extrapolated from in vitro and ex vivo studies, because in vivo analysis of sperm in their native fertilization environment has not been possible. Here we report a functional optical coherence tomography approach that allows, for the first time, in vivo three-dimensional (3D) tracking of sperm behaviors in the mouse oviduct. Motile sperm are identified with their intrinsic dynamic characteristics. Sperm trajectories are reconstructed in 3D with a ...

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    6. Functional optical coherence tomography for live dynamic analysis of mouse embryonic cardiogenesis

      Functional optical coherence tomography for live dynamic analysis of mouse embryonic cardiogenesis

      Blood flow, heart contraction, and tissue stiffness are important regulators of cardiac morphogenesis and function during embryonic development. Defining how these factors are integrated is critically important to advance prevention, diagnostics, and treatment of congenital heart defects. Mammalian embryonic development is taking place deep within the female body, which makes cardiodynamic imaging and analysis during early developmental stages in humans inaccessible. With thousands of mutant lines available and well-established genetic manipulation tools, mouse is a great model to understand how biomechanical factors are integrated with molecular pathways to regulate cardiac function and development. Dynamic imaging and quantitative analysis of the ...

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    7. Multimodality optical coherence tomography and fluorescence confocal scanning laser ophthalmoscopy in a zebrafish model of retinal vascular occlusion and remodeling

      Multimodality optical coherence tomography and fluorescence confocal scanning laser ophthalmoscopy in a zebrafish model of retinal vascular occlusion and remodeling

      Neovascularization in diabetic retinopathy (DR) and age-related macular degeneration (AMD) result in severe vision-loss and are two of the leading causes of blindness. The structural, metabolic, and vascular changes underlying retinal neovascularization are unknown and, thus, there is an unmet need to identify mechanisms of pathogenesis and novel anti-angiogenic therapies. Zebrafish is a robust ophthalmological model because its retina has comparable structure to the human retina and its fecundity and life-cycle enable development of mutant phenotypes of human pathologies. Here, we perform multimodal imaging with OCT and fluorescence confocal scanning laser ophthalmoscopy (cSLO) to identify changes in retinal structure and ...

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    8. Quantitative biometry of zebrafish retinal vasculature using optical coherence tomographic angiography

      Quantitative biometry of zebrafish retinal vasculature using optical coherence tomographic angiography

      The zebrafish is a robust model for studying human ophthalmic function and disease because of its fecundity, life-cycle, and similarities between its retinal structure and the human retina. Here, we demonstrate longitudinal in vivo imaging of retinal structure using optical coherence tomography (OCT) and noninvasive retinal vascular perfusion imaging using OCT angiography (OCT-A) in zebrafish. In addition, we present methods for retinal vascular segmentation and biometry to quantify vessel branch length, curvature, and angle. We further motivate retinal vascular biometry as a novel method for noninvasive zebrafish identification and demonstrated 99.9% accuracy for uniquely identifying eyes from a set ...

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    9. Quantification of the Effect of Toxicants on the Intracellular Kinetic Energy and Cross-Sectional Area of Mammary Epithelial Organoids by OCT Fluctuation Spectroscopy

      Quantification of the Effect of Toxicants on the Intracellular Kinetic Energy and Cross-Sectional Area of Mammary Epithelial Organoids by OCT Fluctuation Spectroscopy

      The ability to assess toxicant exposures of 3D in vitro mammary models that recapitulate the tissue microenvironment can aid in our understanding of environmental exposure risk over time. Longitudinal studies of 3D model systems, however, are cumbersome and suffer from a lack of high-throughput toxicological assays. In this study, we establish a noninvasive and label-free optical coherence tomography (OCT)-based imaging platform for tracking exposure-response relationships in 3D human mammary epithelial organoid models. The OCT-based assay includes metrics that quantify organoid intracellular kinetic energy and cross-sectional area (CSA). We compare the results to those obtained using the 3-(4,5-dimethylthiazol-2-yl ...

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    10. Monitoring of injury induced brain regeneration of the adult zebrafish by using optical coherence tomography

      Monitoring of injury induced brain regeneration of the adult zebrafish by using optical coherence tomography

      The adult zebrafish has pronounced regenerative capacity of the brain, which makes it an ideal model organism of vertebrate biology for the investigation of recovery of central nervous system injuries. The aim of this study was to employ spectral-domain optical coherence tomography (SD-OCT) system for long-term in vivo monitoring of tissue regeneration using an adult zebrafish model of brain injury. Based on a 1325 nm light source and two high-speed galvo mirrors, the SD-OCT system can offer a large field of view of the three-dimensional (3D) brain structures with high imaging resolution (12 μm axial and 13 μm lateral) at ...

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    11. Detection of oral early cancerous lesion by using polarization-sensitive optical coherence tomography: mice model

      Detection of oral early cancerous lesion by using polarization-sensitive optical coherence tomography: mice model

      Oral cancer is the 11th most common cancer worldwide, especially in a male adult. The median age of death in oral cancer was 55 years, 10-20 years earlier than other cancers. Presently, oral cancer is often found in late stage, because the lesion is often flat in early stage and is difficult to diagnose under traditional white light imaging. The only definitive method for determining cancer is an invasive biopsy and then using histology examination. How to detect precancerous lesions or early malignant lesions is an important issue for improving prognosis of oral cancer. Optical coherence tomography (OCT) is a ...

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    12. Imaging whole mouse brains with a dual resolution serial swept-source optical coherence tomography scanner

      Imaging whole mouse brains with a dual resolution serial swept-source optical coherence tomography scanner

      High resolution imaging of whole rodent brains using serial OCT scanners is a promising method to investigate microstructural changes in tissue related to the evolution of neuropathologies. Although micron to sub-micron sampling resolution can be obtained by using high numerical aperture objectives and dynamic focusing, such an imaging system is not adapted to whole brain imaging. This is due to the large amount of data it generates and the significant computational resources required for reconstructing such volumes. To address this limitation, a dual resolution serial OCT scanner was developed. The optical setup consists in a swept-source OCT made of two ...

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    13. Live dynamic analysis of mouse embryonic cardiogenesis with functional optical coherence tomography

      Live dynamic analysis of mouse embryonic cardiogenesis with functional optical coherence tomography

      Hemodynamic load, contractile forces, and tissue elasticity are regulators of cardiac development and contribute to the mechanical homeostasis of the developing vertebrate heart. Congenital heart disease (CHD) is a prevalent condition in the United States that affects 8 in 1000 live births[1], and has been linked to disrupted cardiac biomechanics[2-4]. Therefore, it is important to understand how these forces integrate and regulate vertebrate cardiac development to inform clinical strategies to treat CHD early on by reintroducing proper mechanical load or modulating downstream factors that rely on mechanical signalling. Toward investigation of biomechanical regulation of mammalian cardiovascular dynamics and ...

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    14. Hyperglycemia Alters the Structure and Hemodynamics of the Developing Embryonic Heart

      Hyperglycemia Alters the Structure and Hemodynamics of the Developing Embryonic Heart

      Congenital heart defects (CHDs) represent the most common form of human birth defects; approximately one-third of heart defects involve malformations of the outflow tract (OFT). Maternal diabetes increases the risk of CHD by 3–5 fold. During heart organogenesis, little is known about the effects of hyperglycemia on hemodynamics, which are critical to normal heart development. Heart development prior to septation in the chick embryo was studied under hyperglycemic conditions. Sustained hyperglycemic conditions were induced, raising the average plasma glucose concentration from 70 mg/dL to 180 mg/dL, akin to the fasting plasma glucose of a patient with diabetes ...

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    15. OCE reveals tissue damage caused by heart attacks

      OCE reveals tissue damage caused by heart attacks

      A heart attack, or myocardial infarction (MI), can cause considerable damage to the tissues of the heart, and a better understanding of that damage would be a valuable step towards improved treatment and therapy after the attack. Researchers at the University of Houston have developed a technique based on optical coherence elastography (OCE) that could be used for biomechanical characterization of MI, and be a useful tool to study heart repair. The work was published in Biomedical Optics Express . "About one million people suffer heart attacks every year, and there is currently no cure for the resulting cardiac tissue scarring ...

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    16. Biomechanical assessment of myocardial infarction using optical coherence elastography

      Biomechanical assessment of myocardial infarction using optical coherence elastography

      Myocardial infarction (MI) leads to cardiomyocyte loss, impaired cardiac function, and heart failure. Molecular genetic analyses of myocardium in mouse models of ischemic heart disease have provided great insight into the mechanisms of heart regeneration, which is promising for novel therapies after MI. Although biomechanical factors are considered an important aspect in cardiomyocyte proliferation, there are limited methods for mechanical assessment of the heart in the mouse MI model. This prevents further understanding the role of tissue biomechanics in cardiac regeneration. Here we report optical coherence elastography (OCE) of the mouse heart after MI. Surgical ligation of the left anterior ...

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    17. Prolonged in vivo functional assessment of the mouse oviduct using optical coherence tomography through a dorsal imaging window

      Prolonged in vivo functional assessment of the mouse oviduct using optical coherence tomography through a dorsal imaging window

      The oviduct (or fallopian tube) serves as an environment for gamete transport, fertilization, and preimplantation embryo development in mammals. Although there has been increasing evidence linking infertility with disrupted oviduct function, the specific roles that the oviduct plays in both normal and impaired reproductive processes remain unclear. The mouse is an important mammalian model to study human reproduction. However, most of the current analyses of the mouse oviduct rely on static histology or 2D visualization, and are unable to provide dynamic and volumetric characterization of this organ. The lack of imaging access prevents longitudinal live analysis of the oviduct and ...

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    18. Evaluating the Effects of Maternal Alcohol Consumption on Murine Fetal Brain Vasculature Using Optical Coherence Tomography

      Evaluating the Effects of Maternal Alcohol Consumption on Murine Fetal Brain Vasculature Using Optical Coherence Tomography

      Prenatal alcohol exposure (PAE) can result in a range of anomalies including brain and behavioral dysfunctions, collectively termed fetal alcohol spectrum disorder (FASD). PAE during the 1 st and 2 nd trimester is common, and research in animal models has documented significant neural developmental deficits associated with PAE during this period. However, little is known about the immediate effects of PAE on fetal brain vasculature. In this study, we used in utero speckle variance optical coherence tomography (SVOCT), a high spatial- and temporal–resolution imaging modality, to evaluate dynamic changes in micro-vasculature of the 2 nd trimester-equivalent murine fetal brain ...

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    19. Heart-rate sensitive optical coherence angiography for measuring vascular changes due to posttraumatic brain injury in mice

      Heart-rate sensitive optical coherence angiography for measuring vascular changes due to posttraumatic brain injury in mice

      Traumatic brain injury (TBI) results in direct vascular disruption, triggering edema, and reduction in cerebral blood flow. Therefore, understanding the pathophysiology of brain microcirculation following TBI is important for the development of effective therapies. Optical coherence angiography (OCA) is a promising tool for evaluating TBI in rodent models. We develop an approach to OCA that uses the heart-rate frequency to discriminate between static tissue and vasculature. This method operates on intensity data and is therefore not phase sensitive. Furthermore, it does not require spatial overlap of voxels and thus can be applied to pre-existing datasets for which oversampling may not ...

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    20. Müller Glia Cell Activation in a Laser-induced Retinal Degeneration and Regeneration Model in Zebrafish

      Müller Glia Cell Activation in a Laser-induced Retinal Degeneration and Regeneration Model in Zebrafish

      A fascinating difference between teleost and mammals is the lifelong potential of the teleost retina for retinal neurogenesis and regeneration after severe damage. Investigating the regeneration pathways in zebrafish might bring new insights to develop innovative strategies for the treatment of retinal degenerative diseases in mammals. Herein, we focused on the induction of a focal lesion to the outer retina in adult zebrafish by means of a 532 nm diode laser. A localized injury allows investigating biological processes that take place during retinal degeneration and regeneration directly at the area of damage. Using non-invasive optical coherence tomography (OCT), we were ...

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    21. Measurement of the absolute velocity of blood flow in early-stage chick embryos using spectral domain optical coherence tomography

      Measurement of the absolute velocity of blood flow in early-stage chick embryos using spectral domain optical coherence tomography

      Doppler optical coherence tomography (OCT) is a noninvasive imaging modality that provides quantitative flow information with high spatial and temporal resolution. However, it is only sensitive to the flow velocity vector parallel to the incident beam. To calculate the absolute velocity, it is necessary to obtain the angle between the incident beam and flow field. In this paper, we describe a practical method to measure the Doppler angle based on the structural information of blood vessels extracted from spectral domain OCT images. In this method, a normal sectional scan of the vessel is performed where the probe beam is perpendicular ...

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    22. Feature Of The Week 10/08/2017: Optical Coherence Microscopy as a Novel, Non-Invasive Method for the 4D Live Imaging of Early Mammalian Embryos

      Feature Of The Week 10/08/2017: Optical Coherence Microscopy as a Novel, Non-Invasive Method for the 4D Live Imaging of Early Mammalian Embryos

      Imaging of living cells based on traditional fluorescence and confocal laser scanning microscopy has delivered an enormous amount of information critical for understanding biological processes in single cells. However, the requirement for a high numerical aperture and fluorescent markers still limits researchers’ ability to visualize the cellular architecture without causing short- and long-term photodamage. Optical coherence microscopy (OCM) is a promising alternative that circumvents the technical limitations of fluorescence imaging techniques and provides unique access to fundamental aspects of early embryonic development, without the requirement for sample pre-processing or labeling. In the present paper, we utilized the internal motion of ...

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

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

      Several optical imaging techniques have been applied for high-resolution embryonic imaging using different contrast mechanisms, each with their own benefits and limitations. 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). RI-OCT overcomes optical penetration limits of traditional OCT imaging that prohibit full-body imaging of mouse embryos at later stages by imaging the samples from multiple angles. SPIM enables high-resolution, 3D imaging with less phototoxicity and photobleaching than laser scanning confocal microscopy (LSCM) by illuminating the sample with a focused sheet of light. Side by ...

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    24. Evaluating biomechanical properties of murine embryos using Brillouin microscopy and optical coherence tomography

      Evaluating biomechanical properties of murine embryos using Brillouin microscopy and optical coherence tomography

      Embryogenesis is regulated by numerous changes in mechanical properties of the cellular microenvironment. Thus, studying embryonic mechanophysiology can provide a more thorough perspective of embryonic development, potentially improving early detection of congenital abnormalities as well as evaluating and developing therapeutic interventions. A number of methods and techniques have been used to study cellular biomechanical properties during embryogenesis. While some of these techniques are invasive or involve the use of external agents, others are compromised in terms of spatial and temporal resolutions. We propose the use of Brillouin microscopy in combination with optical coherence tomography (OCT) to measure stiffness as well ...

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