Fig. 1

MR embedding for SBF-SEM. A Samples infiltrated with pure resin (Additional file 1) were poured into a glass petri dish to enable inspection of their integrity under the stereomicroscope. B Optional brief dipping in acetone. C Draining the outer resin. Samples (removed from acetone or directly from the resin) were transferred onto a piece of filter paper, moved around and then placed on cigarette paper. D Sample after removal of outer resin. E Mounting on a pin. A SBF-SEM pin was placed under the stereomicroscope and using a toothpick a small drop of resin was made in the centre. Using clean forceps the sample was placed on the side of the pin to see the position of the ROI. F Sample was placed on the drop in a desired orientation for imaging. G Sample on the pin after it was polymerized. Compare with the traditional embedding in a block (inset). H Minute sample polymerized on a resin pillar, which supports it from the bottom (left); elongated sample is supported from the side (right). Samples: A–G O. cincta, H A. dispar. Scale bars: A, C, 2 cm; D, 1 mm; E, G, inset in G, 2 mm; H left, 400 μm; H right, 500 μm