What purpose do the cell divisions that occur immediately after fertilization serve? What is the initial cluster of cells called?
Following fertilization, several miotic divisions occur almost immediately. The cleavages occur in rapid succession and do not produce any growth in the overall size of the embryo. Rather, the early cleavages help re-establish a more normal ratio of nuclear to cytoplasmic materials than exists in the oversized ovum. This initial cluster of cells is called a morula.
