Name: mature oocyte stage
ECAO ID: 0000090
Definition: "A mature female gamete that has achieved its meiotic maturation and in which the female pronucleus is visible. The mature oocyte is arrested in G1 phase and its average size is 80 to 100 µm. It is surrounded by a transparent jelly coat that is about 30 µm thick. It is competent to fertilization and it is located in the female gonad where it may be stored for weeks to months before its release in sea water by spawning. In the P. lividus species, the mature female gametes are characterized by the presence of pigment granules concentrated in a subequatorial band. This band is classically called the pigment band and allows to visualize the first embryonic axis, i.e. the animal-vegetal axis, which is perpendicular to the band."
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