Choosing sides: establishment of polarity in zygotes of fucoid algae

The acquisition and expression of polarity during early embryogenesis underlies developmental pattern. In many multicellular organisms an initial asymmetric division of the zygote is critical to the determination of different cell fates of the early embryonic cells. Zygotes of the marine fucoid algae are initially apolar and become polarized in response to external cues. This results in an initial asymmetric division of the zygote. Subsequent divisions occur in a highly ordered spatial and temporal pattern. A combination of cell biological and biochemical studies is providing new details, and some controversies concerning the mechanisms by which zygotic polarity is acquired and amplified. Here, we discuss some of the more recent studies that are allowing improved understanding of polarization in this system.