Fig. 2

TDX16 development and transition into TDX16-DE. A Very small TDX16 cells with electron-dense HGBs multiplied by asymmetric division in the senescent H. pluvialis cell, scale bar 5 μm. B Small DTX16 cells filled up the cellular space of a senescent H. pluvialis cell, scale bar 0.5 μm. C Five TDX16 cells within a sporangium, scale bar 1 μm. D A TDX16-DE cell contains a large “e-shaped” chloroplast (C) with an embedded pyrenoid (P), a nucleus (N), a mitochondrion (M) and two vacuoles (V), scale bar 0.5 μm