In spermatogenesis the sex cell divides (from 46 chromos to 23), and then divides again to produce 4 haploid cells that become sperm. In oogenesis, the sex cell divides into one ovum and a polar body in the first division, and in the second division the ovum divides again into a haploid (ovum) and a polar body, and the polar body divides into two more polar bodies. Polar bodies are non-functional, so only one ovum is produced in the end. Spermatogenesis produces millions of sperm, while oogenesis only produces one mature ovum a month.
