Life cycle of a centric diatom. I
The vegetative phase
As a result of the unique type of cell division in diatoms, average cell size decreases during the vegetative phase. In linear dimensions (e.g. the diameter of circular diatoms, the length of bipolar diatoms), the smallest are often less than half the size of the largest. All cell divisions during the vegetative phase are mitotic and all vegetative cells are diploid.
The illustrations are modified by DG Mann from the originals used by Mann in Round et al. (1990, fig. 55)
Chepurnov, V.A., Mann, D.G., Sabbe, K. & Vyverman, W. (2004). Experimental studies on sexual reproduction in diatoms. International Review of Cytology 237: 91-154.
Round, F.E., Crawford, R.M. & Mann, D.G. (1990). The diatoms. Biology and morphology of the genera. Cambridge University Press, Cambridge.