Stage 1: H+0 post-fertilization - 1 cell stage.
Stage 2: H+1 post-fertilization - 2 cells stage
Stage 3: H+1.5 post-fertilization - 4 cells stage
Stage 4: H+1.75 post-fertilization - 8 cells stage
Stage 5: H+2 post-fertilization - 16 cells stage
Stage 6: H+2.5 post-fertilization - Blastula
Stage 7: H+4 post-fertilization - Gastrula - Apparition of the blastopore
Stage 8: H+7.25 post-fertilization - Tailbud stage - Formation of the larva tail
Stage 9: H+9 post-fertilization - Elongation of the tail
Stage 10: H+15 post-fertilization - Apparition of the larva eyes - Larva ready to hatch
Commonly, ascidians hatch about 12 h post-fertilization, but in A. glabra, the embryonic development seems to be slightly longer (about 15 h post-fertilization) (Satoh, 2003). Another difference is that the cell cycle speed should slightly decrease between stages 2 and 5 (from 2 cells to 16 cells) due to a longer interphase whereas, in A. glabra, a minor increase in the cell cycle speed was observed (McDougall et al., 2011).