An orientation-independent DIC microscope allows high resolution imaging of epithelial cell migration and wound healing in a cnidarian model
Epithelial cell dynamics can be difficult to study in intact animals or tissues. Here we use the medusa form of the hydrozoan Clytia hemisphaerica, which is covered with a monolayer of epithelial cells, to test the efficacy of an orientation-independent differential interference contrast microscope for in vivo imaging of wound healing. Orientation-independent differential interference contrast provides an unprecedented resolution phase image of epithelial cells closing a wound in a live, nontransgenic animal model. In particular, the orientation-independent differential interference contrast microscope equipped with a 40x/0.75NA objective lens and using the illumination light with wavelength 546 nm demonstrated a resolution of 460 nm. The repair of individual cells, the adhesion of cells to close a gap, and the concomitant contraction of these cells during closure is clearly visualized.Lay description
In this paper, we show how a newly developed microscopic technique, orientation-independent differential interference contrast (OI-DIC), can give us an unprecedented look at dynamic cell behaviour in a transparent tissue. As an example of the power of the new microscope to address biological questions, we used it to examine wound healing in the small, transparent jellyfish Clytia hemisphaerica. Clytia is covered with a single layer of epithelial cells. Upon wounding, the epithelial cells migrate inwards from the margins of a wound to permanently close it. The process looks remarkably like processes that occur in vertebrates such as ourselves, suggesting that insights gained in Clytia wound healing may have a far reaching implications to basic science questions and even to the treatment of wounds in the clinic. The orientation-independent differential interference contrast microscope provides halo-free phase images of live wound healing at the highest resolution, allowing the detection of details and events not visible using standard DIC or phase contrast microscopy. These results show that orientation-independent differential interference contrast microscopy is an important new tool for studying cells and cell dynamics in vivo.