Note
The mature oocytes of the marine calanoid copepod, Centropages velificatus, contain two morphologically distinct populations of cortical vesicles that undergo sequential exocytoses at the time of spawning. The contents of the primary cortical vesicles are released first and form the primary egg envelope. This is followed by the exocytosis of the secondary cortical vesicles. These contain numerous intracisternal granules that, upon release into the perivitelline space, transform into a mass of fine fibers. The continual accumulation of fibers constitutes an extracellular matrix between the primary envelope and the egg's plasmalemma.