The egg cell forms in an ovary with the participation of the FSH (follitropin, follicle-stimulating hormone). In the natural cycle, one, or very rarely several egg cells develop. Each egg cell lies in one follicle. The mature egg cell forms at the stage of second meiotic division; the external presentation of this stage is the presence of a polar body. Each cell is surrounded by a wreath of granulosa cells, thus forming the so-called cumulus.