As major accomplishments and breakthroughs in centrosome research had been achieved by Theodor Boveri in reproductive cells with the invertebrate sea urchin being an ideal model system for such studies on fertilization, cell division, and embryo development, these studies also gave rise to Boveri's brilliant concept regarding cancer cells. He discovered that eggs fertilized with two sperm resulted in tripolar mitosis and abnormal cell division, similar to cells observed in cancer tissue.