Formation of
coccoliths. (A,B) SEM images of Coccolithus
braarudii coccoliths. The diploid life stage forms intricate
crystal morphologies (A), while the haploid stage forms simple rhombohedral
crystals (B). (C–F) Cellular anatomy of Pleurochrysis
carterae. (C, D) Sections in fixed cells show in (C) the
various cell organelles (Chl., chloroplast; Nu., nucleus; magenta
arrowheads indicate coccolith vesicles), and a high magnification
image shows in (D) a coccolith vesicle (blue arrowheads indicate the
crystals, yellow arrowhead indicates the organic base plate). Reprinted
with permission from ref (22). Copyright 2020 Elsevier. (E) 3D rendering of a cryo-fixed
cell. The inset shows the vacuole (light brown) filled with Ca–P-rich
bodies (red) and coccoliths (blue). (F) 3D rendering of a live cell
using confocal microscopy, showing several dense intracellular pools
stained with DAPI (red); chloroplasts are in green. Reprinted with
permission from ref (18). Copyright 2021 Wiley-VCH GmbH.