Ovum vs. Oocyte — What's the Difference?
By Fiza Rafique & Urooj Arif — Updated on May 2, 2024
Ovum refers to a mature female reproductive cell ready for fertilization, whereas an oocyte is an immature egg in the stages before it develops into an ovum.
Difference Between Ovum and Oocyte
Table of Contents
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Key Differences
The ovum is the final stage of the female gamete that is capable of being fertilized, while the oocyte represents an earlier stage of development that occurs before it becomes an ovum.
Oocytes are formed during fetal development in females and undergo a process called oogenesis, whereas the ovum is the product of the final maturation steps of this process.
Oocytes can be found in various developmental stages within the ovaries, including primary and secondary forms, on the other hand, the ovum is a singular, mature entity ready for fertilization.
Hormonal cues trigger the maturation of oocytes into an ovum, which occurs during the menstrual cycle; in contrast, the ovum's existence is transient, surviving only about 12-24 hours post-ovulation unless fertilized.
The oocyte is surrounded by supportive cells and structures that nourish and protect it during its development, whereas the ovum, once released, lacks these structures as it moves into the fallopian tube.
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Comparison Chart
Definition
Mature female gamete ready for fertilization
Immature egg cell in developmental stages
Development Stage
Final, post-meiotic stage
Pre-meiotic and meiotic stages
Location
Released into the fallopian tube
Located in the ovaries
Lifespan
12-24 hours post-ovulation
Indefinite until maturation triggers
Compare with Definitions
Ovum
Ready for fertilization.
The presence of an ovum in the fallopian tube initiates the possibility of conception.
Oocyte
An immature egg developing in the ovaries.
An oocyte undergoes several stages of maturation before becoming an ovum.
Ovum
Capable of forming a zygote upon fertilization.
The fertilized ovum begins dividing rapidly to form an embryo.
Oocyte
Undergoes division through meiosis.
Oocytes are arrested in their development until hormonal cues trigger continuation.
Ovum
Final product of oogenesis.
The ovum awaits fertilization in the fallopian tube.
Oocyte
Forms part of the ovarian reserve.
Women are born with their lifetime supply of oocytes.
Ovum
Lifespan is limited to a short period post-ovulation.
If not fertilized, the ovum disintegrates and is expelled.
Oocyte
Has potential to mature into an ovum.
Each menstrual cycle gives the oocyte a chance to mature.
Ovum
Mature female reproductive cell.
The ovum must be fertilized within 24 hours of being released.
Oocyte
Surrounded by a layer of cells called the cumulus oophorus.
The oocyte is nurtured and protected by surrounding cells.
Ovum
The mature female gamete of an animal; an egg.
Oocyte
An oocyte (UK: , US: ), oöcyte, ovocyte, or rarely ocyte, is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell.
Ovum
(cytology) The female gamete in animals; the egg cell.
Oocyte
A diploid cell from which an egg or ovum develops by meiosis. A primary oocyte divides to produce a polar body and a secondary oocyte, which divides again to produce the ovum and another polar body.
Ovum
A more or less spherical and transparent cell, which by a process of multiplication and growth develops into a mass of cells, constituting a new individual like the parent; an egg, spore, germ, or germ cell. See Illust. of Mycropyle.
Oocyte
(cytology) A cell that develops into an egg or ovum; a female gametocyte.
Ovum
One of the series of egg-shaped ornaments into which the ovolo is often carved.
Oocyte
A female gametocyte that develops into an ovum after two meiotic divisions
Ovum
The female reproductive cell; the female gamete
Common Curiosities
What happens to the oocyte if it does not become an ovum?
If not triggered to mature, the oocyte remains in the ovaries and may either deteriorate over time or remain viable for future cycles.
What is an oocyte?
An oocyte is an immature egg cell, still in development within the ovaries.
How does an oocyte become an ovum?
An oocyte matures into an ovum through a process triggered by hormonal changes, typically during the menstrual cycle.
What is an ovum?
The ovum is the mature form of a female reproductive cell ready for fertilization.
Are oocytes present from birth?
Yes, females are born with all their oocytes already present in their ovaries.
What structural differences exist between an ovum and oocyte?
The ovum is larger, lacks surrounding nourishing cells when released, whereas oocytes are smaller and surrounded by nurturing cells in the ovaries.
Can an ovum regenerate if it is not fertilized?
No, once the ovum is not fertilized, it disintegrates and cannot regenerate.
How is the lifespan of an oocyte different from that of an ovum?
Oocytes can remain viable for years within the ovaries, while the ovum's lifespan is limited to a few hours post-release if not fertilized.
How long does an ovum live once it is released?
The ovum can live for about 12-24 hours after being released during ovulation.
What role do hormones play in the development of an oocyte?
Hormones such as follicle-stimulating hormone (FSH) and luteinizing hormone (LH) regulate the growth and maturation of oocytes.
What is the main difference in the location of ovum and oocyte?
The ovum is found in the fallopian tube post-ovulation, while oocytes reside in the ovaries.
How many oocytes does a woman have?
A woman is born with 1 to 2 million oocytes, which decrease in number throughout her life.
Why can't an oocyte be fertilized?
Oocytes are not fully mature and lack the necessary cellular structures for fertilization.
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Written by
Fiza RafiqueFiza Rafique is a skilled content writer at AskDifference.com, where she meticulously refines and enhances written pieces. Drawing from her vast editorial expertise, Fiza ensures clarity, accuracy, and precision in every article. Passionate about language, she continually seeks to elevate the quality of content for readers worldwide.
Co-written by
Urooj ArifUrooj is a skilled content writer at Ask Difference, known for her exceptional ability to simplify complex topics into engaging and informative content. With a passion for research and a flair for clear, concise writing, she consistently delivers articles that resonate with our diverse audience.
