Facilities:
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Laser Scanning Confocal (Leica SP6) Our principle imaging microscope is used for both live and prepared samples. The motorized stage has been modified to support stable imaging of F-actin dynamics and high speed XZ time-lapse sequences. Supports light-weight microaspiration w/ electrical stimulation. The manual stage can support larger or heavier devices from custom-fabricated tissue stretchers to multi-well Flexcell chambers. |
nanoNewton Force Measurement Device (nNFMD; aka "Histowiggler 2k7")
This device uses uniaxial unconfined compression to measure the viscoelastic properties of frog embryonic tissues. Briefly, a regularly shaped block (think "brick") of embryonic tissue prepared by microsurgery is held under a spring and compressed. The tissue resists compression with a force that is measured by the deflection of a stiff spring (really a long thin optical fiber). The resistance force, the degree of compression or strain, and the cross-sectional area of the tissue along the axis of compression are used to calculate the viscoelastic properties of the embryonic tissue. The contribution of molecular composition of the tissue can be tested by knock-down or inhibitor studies. The contribution of specific mechanical structures can be tested by microsurgerically removing the structure, microsurgical duplication, or molecularly disrupting the formation of the structure. The limitations of this approach is that it requires microsurgical removal and shaping of tissues into regularly shaped blocks. The smallest structure tested by the nNFMD is about 200um x 300um x 600 um and contains approximately 5000 embryonic frog cells and their extracellular matrix.
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Micro-aspiration Device (aka "Embryo Sucker") This device uses pressure to micro-aspirate a small patch of tissue into a wide cylindrical channel (~120 um in diameter) to measure the viscoelastic properties of frog embryonic tissues. Any patch of tissue from the embryo can be micro-aspirated but informative results are generally only found when the tissue is thicker than the diameter of the channel. Very small pressure differences across the face of the channel are generated by lowering the water level in the adjoining reservoir by a small amount (~0.5 to 1 mm). As pressure is lowered a small patch of the embryo is pulled into the cylindrical channel. The amount of tissue that moves into the channel and the pressure difference are used to calculate the viscoelastic properties of the embryonic tissue. The advantages of this approach is that embryos do not need to be 'taken-apart' to measure mechanical properties. This non-destructive approach allows the tested embryo to continue developing and allows further testing or assessment. The smallest structure tested by our device is about 120 um diameter channel x 120 um deep and contains between 5 and 40 epithelial embryonic frog cells, deep cells, and associated extracellular matrix. |
Multiposition Time-lapse Stereoscope Rig We have mounted a computer controlled XY-stage at the focus of a stereoscope mounted with a CCD camera. The stage and camera are controlled by NIH ImageJ and the microManager plugin. This rig allows simultaneous acquisition of multiple time-lapse sequences. |
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Epifluorescence Stereoscope Rig A fluorescence light source and filter blocks allow imaging of fluorescently labeled samples or screening of frog embryos expressing a fluorescent protein. A color camera allows recording images from these samples using NIH ImageJ. |
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Time-lapse Stereoscope Rig A sterescope with a grey-scale CCD camera mounted on the video-port allows time-lapse collection of living tissues or documentation of tissues and embryos. |
Dissecting Stereoscopes We have a set of dissection stereomicroscopes to use for microsurgery or for constructing small devices. |
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