Transmission electron micrographs (TEM) of Rapaza viridis n. gen. et sp. showing details of two types of chloroplasts. A. Transverse TEM showing the chloroplast of R. viridis and 16 pellicle strips (arrowheads). Pairs of thylakoid membranes (arrows) penetrate the pyrenoids (Py). The black arrow indicates the the pellicle strip that is shown in Figure 5B. B. Higher magnification TEM of Figure 5A focusing on the three membranes that surround the chloroplast of R. viridis (arrowheads) and the associated stacks of thylakoids (Ty). The black arrow indicates the the pellicle strip that is shown in Figure 5A. C. High magnification TEM showing electron-dense structures surrounded by a single membrane (arrowheads) that are situated near a chloroplast. D. TEM showing two different types of chloroplasts: The chloroplast of Tetraselmis sp. (Tcp) contains an eyespot (arrowheads); the chloroplast of R. viridis (Rcp) does not. E. Longitudinal TEM showing an engulfed Tetraselmis cell, including the nucleus (N), pyrenoid (Py) and associated starch (S) and chloroplast (Cp). Arrowheads indicate the pellicle strips of R. viridis. F. High magnification TEM showing the food vacuole of R. viridis (R-arrow) and the cell membrane of the engulfed Tetraselmis cell (T-arrow). White arrowheads mark the two membranes that surround the chloroplast of Tetraselmis sp. Black arrowheads mark the pellicle strips of R. viridis. G. High magnification TEM showing the eyespot (arrows) within the chlorplasts of Tetraselmis sp. Scale bars 1 μm in A, C and G; 200 nm in B and F; 4 μm in D and E.
Yamaguchi et al. BMC Evolutionary Biology 2012 12:29 doi:10.1186/1471-2148-12-29