Single aster consisting of microtubules radiating in all directions from the centrosome, a microtubule organizing center found in almost all animal cells. This false color image was generated by the LC-PolScope, a new type of polarized light microscope developed by the Oldenbourg Lab.
Left: LC-PolScope image of a thin polycrystalline calcite film of uniform thickness. In this false colour image hue represents the measured in-plane orientation of the optic axis and brightness is proportional to the inclination angle of the optic axis. Each crystalline domain has nearly uniform hue and brightness, due to the uniform birefringence of each domain.
Right: Polarized light field image of the same calcite film as shown on the left. Hue represents slow axis orientation and brightness the amount of retardance measured. The image consists of an array of 21 x 37 disk-shaped images, each disk representing a conoscopic birefringence map.
The cell in the center is a primary spermatocyte from the crane fly, Nephrotoma suturalis (Preparation by James R. La Fountain, University at Buffalo.) With the LC-PolScope, birefringence is revealed with striking contrast, regardless of specimen orientation, and thus, the spindle fibers, composed of bundled microtubules, are clearly imaged as bright structures on the non-birefringent (or weakly birefringent) background cytoplasm. At the periphery of the spindle is a mantle of elongated mitochondria, as well as numerous highly birefringent vesicular structures. The pole-to-pole distance is approximately 25µm.
Differential transmittance of Siemens star in metal MBL/NNF target. Logarithmically enhanced LUT. The hue gives the orientation of the high transmittance axis, which is radially aligned, except near the center where it has azimuthal alignment.
Actinosphaerium, a single celled, heliozoan protist, imaged with the LC-PolScope in pseudo-color. The image is an optical section through the spherical cell body and radially arranged pseudopodia, which owe their stiffness to an array of microtubules that reach into the cell interior. Diameter of cell body about 200 µm.
Fluorescence image of a living cell (MDCK) expressing septin molecules linked to green fluorescent protein (GFP). The image was recorded with the Fluorescence LC-PolScope which reveals the polarized fluorescence of septin fibers in false color. Each hue is associated with a different orientation of the GFP dipoles, which in turn reflect the fiber orientation, as septin-GFP molecules are locked into the fiber assembly. The white color of the fluorescence from the cytosol, on the other hand, reveals the lack of a common alignment of septin-GFP molecules suspended in the cytosol. Credit: Amy Gladfelter/Dartmouth College and Rudolf Oldenbourg/MBL
Polarized light image of single lobe from 250-µm thick brain slice of the chick cerebellum. In this contrast enhanced, false color image, hue gives the orientation of the slow axis of birefringence, which is aligned perpendicular to the neuronal fiber bundles. Related publication: Koike-Tani, M., T. Tani, S. B. Mehta, A. Verma and R. Oldenbourg. 2013. Polarized light microscopy in reproductive and developmental biology. Molecular Reproduction and Development. Electronic publication DOI: 10.1002/mrd.22221. Image recorded by Maki Koike-Tani, MBL.
Mitotic spindle isolated from fertilized sea urchin egg. Microtubule bundles radiate out from two centrosomes which appear dark; chromosomes are visible between the two star formations. (Preparation by John Murray, University of Pennsylvania.) This image of an unstained specimen was recorded by the LC-PolScope.
