Ova, also known as egg cells, are the female reproductive cells in many organisms, including humans. They are produced in the ovaries and play a crucial role in reproduction. Each ovum contains genetic material and is typically released during the menstrual cycle in a process called ovulation. In humans, ova are much larger than sperm cells and are essential for fertilization. When a sperm cell from a male fertilizes an ovum, it can lead to the development of an embryo. This process is fundamental to the reproductive systems of many species, including mammals and birds.