Image I: anterior (A) <-> posterior (P)
Image II: A <-> P
A 2-cell C. elegans embryo.
Image III: A (with mouth) <-> P (with tail)
An adult C. elegans. In a single-cell embryo, the difference in anterior and posterior is already established. In the 2-cell embryo these differenences are more pronounced (large vs small cells). In the adult worm, there are very distinct structures in the anterior versus posterior.
Basic components in the embryo:
|Zygote : This is taken soon after paternal (dad) pro-nucleus entered the egg.||This is still an one-cell embryo (instead of 2-cell) with mother pro-nucleus at the left and father pro-nucleus at the right. The cleavage in the middle of the embryo is pseudo-furrow although it looks like 2 cells.||The yellow bumps in the embryo are the refractile cytoplasmic organelles. They move around as the embryo divides.|
Left: One cell embryo develops into two-cell embryo. Right: matching animation
From the phenomenon and cell polarity animation, polarization can be observed as the generation of two unequal-size daughter cells and the unequal distribution of cellular components in the two daughter cells, e.g.: components on cell membrane (notice the distribution of the purple and orange lines).