Oval eggs are normal, and mature egg cells are round or oval in shape. The egg is a reproductive cell produced by the ovary and is the largest cell in the body. Eggs have a spherical appearance and develop from oocytes, which are already present in large numbers in the ovaries during the female embryonic stage. As the ovaries mature, a large number of oocytes are eliminated, and only 300-400 eggs develop. Women have two ovaries, the left and right, which ovulate alternately each month, usually releasing one mature egg each month. A mature egg cell is usually 18-25 millimeters in diameter, and the follicle is translucent with clear borders. After ovulation by the ovary, the egg enters the fallopian tube through the egg pick-up action of the fallopian tube and waits for fertilization. The survival time of the egg is usually around 48 hours, and if it is able to be fertilized it develops into a fertilized egg, and the egg that is not able to be fertilized will die.