260 J.M. Seguí-Simarro et al.
However, the full extent of the CPAM system and its importance for cell
plate formation only became evident when the cryofixed dividing cells were
analyzed by means of electron tomography (Otegui et al. 2001; Otegui and
Staehelin 2004; Seguí-Simarro et al. 2004; Austin et al. 2005). Thus, as men-
tioned above, the definition of the phragmoplast initials during somatic type
cytokinesis includes the formation of multiple CPAMs in the equatorial plane
within which vesicles accumulate and the first vesicle fusion intermediates
can be observed (Figs. 2B, 4A). The lateral enlargement of the phragmoplast