Diatom Reproduction

Diatoms, as with most protists, undergo vegetative reproduction by cell fission. Diatoms are constrained by the their hardened cell walls, so that cell division results in the two daughter cells being confined within the two halves of the parental cell wall. Each daughter cell then produces a new half of a cell wall, grows, and separates from its sister cell (see diagram).

In colonial forms, the new cell walls can remain conncected to one another, forming chains of cells as the diatoms divide. These can appear as ribbons (for pennate diatoms) or cylinderical chains (for centric diatoms). Since each new cell wall is produced within the confines of the parental walls, there is a progressive reduction in the average size of the cell wall (and the cell) as the population divides. Larger cell sizes are regained through sexual reproduction coupled with the growth of a zygote prior (fig. 2) to the formation of a hardened cell wall.

Diatoms are among the first cells analyzed for cell division (fig.1) and their highly ordered mitotic spindle allowed the first clear model of the development of microtubule organization and the development of the spindle during eukaryotic mitosis.