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Clevage

C. elegans exhibit rotational holoblastic cleavage. When cleavage begins 4 founder cells are created. The cell division in C. elegans is Asymmetrical. This means that during the first cleavage the cleavage furrow is located asymmetrically along the axis of the egg. Axis determination in C. elegans is determined by elongated axis found during cell division. The decision of which end of the cell will become anterior or posterior is determined by which end the sperm cell enters the egg. When the sperm enter the oocyte Cytoplasm the centriole pushes the male nucleus to the nearest end of the oblong oocyte this end is the posterior pole. The second anterior to posterior asymmetry is seen shortly after this. P-granules move towards the posterior end of the zygote so they can only enter the blastomere. P-granules are ribonucleoprotein that function in specifying the germ cells.

Gastrulation Gastrulation in C. Elegans starts early compared to other organisms, it begins just after the formation of the P4 generation in 24-cell Embryo’s. Cell movement begins when two epidermal cell precursors Ea and Ep migrate from the surface of the embryo into the blastocoel as ingression occurs Ea and Ep ingress, there apical surfaces separate from the envelope and are covered by six cells, Three MS cells Two AB progeny and P4. After Endodermal cells have completed ingression, Mesodermal cells follow which is followed by germ cells. Ingressing cells accumulate non-muscle myosin, at the apical surface, when ingression happens, when ingression is finished myosin accumulates at the aucak surfaces and undergo a morphogenic changed called apical constriction. during apical constrictiction the width of the apical surfaces decreased, this changes the shape of the cell.