Light Sheet Fluorescence Microscopy techniques, such as selective plane illumination microscopy (SPIM; Huisken et al., 2004), has proven a powerful tool to image developmental processes in vivo with fast, high-resolution optical sectioning over large volumes (Huisken and Stainier, 2009). However, an intrinsic limitation of all fluorescence microscopy techniques, including SPIM, is their inability to image unlabeled structures. The fluorescent signal therefore lacks anatomical context, and phenomena like growth or migration of labeled features may be hard to interpret. A common workaround is imaging unspecific autofluorescence, but this is not an option for in vivo studies because detection of low level autofluorescence requires high illumination power, causing serious phototoxicity.
Optical projection tomography (OPT; Sharpe et al., 2002) has been developed to exploit the bright-field contrast of the sample by acquiring several light transmission images (or projections) from different directions; the 3D structure of the sample is then reconstructed using a back-projection algorithm (Kak and Slaney, 1988). Therefore Optical Projection Tomography can be used as a valuable tool to observe the whole anatomy of living translucent organisms complementing and improving the analysis of SPIM data*.
*Huisken et all, Development (2015) 142, 1016-1020