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Example Research – Cell Polarity

The uneven division during the first cell cycle of C. elegans embryogenesis is illustrated as an example cell biology research.

Image I: anterior (A) <-> posterior (P)

A one-cell C. elegans embryo (right after sperm enters oocyte).

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.

Understanding the Early C. elegans Embryo

Basic components in the embryo:

Additional Information

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.

A Close Look with Animation

Left: One cell embryo develops into two-cell embryo. Right: matching animation

     

Animation and Bioclips of Cell Polarity & Cell Division

Polarization

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).

Research Questions

  1. What components are distributed differently?
  2. How important is it to have the cellular components polarized?
  3. What are the functions of the polarized cellular components?
  4. What are the spatial and temporal relationship between the polarized and non-polarized components?

Credits

  1. Images of 1-cell and 2-cell embryo: Kevin O’Connell, National Institute of Diabetes & Digestive & Kidney Diseases (NIDDK).
  2. Image of the adult worm: Bob Goldstein, The University of North Carolina at Chapel Hill