Fig 1.
Schematic of the visOCM setup for C. elegans imaging.
Light from a laser source with a broad spectrum in the visible range (A, inset) is collimated by lens L1 and split by beam-splitter BS1 into a sample (green) and reference (blue) arm. In the sample arm, the axicon lens generates a Bessel-like illumination beam which is then guided to the tube lens (TL) and objective by the X-Y galvo-scanner unit. The back-reflected light (red) from the sample (B, inset) is recombined with the reference arm by beam-splitter BS2 and focused by L2 into the detection fiber. Finally, the spectrometer (C, inset), records the interference pattern which is processed to yield a depth profile of the C. elegans structure. The data processing steps are illustrated in S1 Fig. Scale bars: 25 μm.
Fig 2.
3D volume rendered images and cut sections of a young adult wild-type C. elegans.
(A) 3D visualization of the body surface of the nematode. The location of the following cut sections are highlighted. (B, C) Sections along the y-axis. (D, E) En face (x-y) cuts. (F-H) Transverse sections. The high contrast and resolution of our visOCM setup reveal all major anatomical features of the worm. The reproductive tissue, including germ cells, oocytes and embryos, can be particularly well observed in these sections. See also S1 Video for an en face scan through the whole C. elegans.
Fig 3.
Anatomy of the C. elegans as revealed by visOCM.
(A, B) En face projections at two different depths, and (C) side view at the location highlighted in (B). Scale bars indicate 50 μm. (D) Top: A 3D rendered model of the head with the pharynx highlighted in green. Bottom: Maximum-intensity projection through the entire animal’s head. (E) En face view (top) and corresponding transverse sections (bottom), with the lumen of the intestine highlighted in yellow. (F) Zoom regions of the reproductive system showing germ cells, oocytes, spermatheca, embryos and the vulva. The 3D sub-micrometer resolution and the intrinsic contrast of our technique enable a clear and detailed visualization of tissue structures down to the sub-cellular level (see also S2 Video).