Oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics.


Oligomenorrhoea is infrequent or, in occasional usage, very light menstruation. More strictly, it is menstrual periods occurring at intervals of greater than 35 days, with only four to nine periods in a year. Menstrual periods should have been…


Oocyte is an immature ovum or egg cell.


Orgasm is the sudden discharge of accumulated sexual excitement during the sexual response cycle, resulting in rhythmic muscular contractions in the pelvic region characterised by sexual pleasure. Experienced by males and females, orgasms are controlled by the…


The ovary is an organ found in the female reproductive system that produces a cell called an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by…