ovarian teratoma An ovarian tumor that is usually benign and typically contains a diversity of tissues. An ovarian teratoma develops from a totipotential germ cell—a primary oocyte—that is retained within the ovary. Totipotential cells can give rise to all orders of cells that are necessary to form mature tissues and often recognizable structures, such as…
ovary The female gonad, one of a pair of reproductive glands in women. The ovaries are located in the pelvis, one on each side of the uterus. Each ovary is about the size and shape of an almond. The ovaries produce eggs (ova) and female hormones. During each monthly menstrual cycle, an egg is released…
ovary, dermoid cyst of the See ovarian teratoma.
ovary cyst, follicular See cyst of the ovary, follicular.
overgrowth Excessive growth. Also sometimes called gigantism.
overgrowth syndrome A condition with multiple features, most notably excessive growth. A number of overgrowth syndromes affect children, such as fragile X syndrome. Excessive growth of specific body parts is also a feature of a number of disorders, such as Beckwith-Wiedemann syndrome, in which there is macroglossia (a large tongue due to overgrowth of the…
overload, iron See excess iron.
over-the-counter drug A drug that is available without a prescription, in contrast to prescription drugs that require a physician’s order. Abbreviated OTC.
overweight Weighing more than is healthy for a particular body type and build. Overweight is often defined as having a body mass index (BMI) from 25 up to 30. See also body mass index; obese.
ovulation The release of the ripe egg (ovum) from the ovary. The egg is released when the cavity surrounding it (the follicle) breaks open in response to a hormonal signal. Ovulation occurs around 14 or 15 days from the first day of the woman’s last menstrual cycle. When ovulation occurs, the ovum moves into the…
ovum An egg within the ovary of the female. An ovum can combine with sperm to form a zygote.
oximetry The process of determining the level of oxygenation in arterial blood, an important measure of whether the heart and lungs are working properly. Oximetry may be done continuously during certain medical treatments or surgery, or it may be done sporadically to monitor a patient’s health.