The early mitotic divisions are called cleavage. In deuterostomes, the first two cell divisions are along the axis determined by the animal and vegetal poles. These poles are defined by uneven distribution of components of the cytoplasm. The first four cells get material from both poles and any one of them could develop into an entire individual. For this reason, the first two cleavages are said to be indeterminate. The third cleavage is perpendicular to the axis and the daughter cells include cytoplasm from either the animal or vegetal pole. None of these eight cells can form an entire individual, so the third cleavage is determinate.
