Egg: Meaning, Ovulation, Fertilization, and Reproductive Health

In humanreproduction:

• eggs develop in the ovaries;
• an egg may be released during ovulation;
• sperm may reach and fertilize the egg;
• a fertilized egg becomes a zygote;
• the zygote may implant in the uterus and develop further.

An egg is much larger than a sperm cell, but it is still microscopic and cannot normally be seen without magnification.

Simple examples include:

• An egg may be released during ovulation.
• A sperm must reach an egg for fertilization to occur.
• An unfertilized egg usually breaks down naturally.
• An egg may be frozen for future fertility treatment.
• Producing an egg does not determine a person’s gender identity.

• human egg;
• mature egg;
• unfertilized egg;
• fertilized egg;
• release an egg;
• retrieve an egg;
• freeze an egg;
• donate an egg.

Examples include:

• The ovary released an egg during ovulation.
• The clinic retrieved several eggs for fertility treatment.
• The egg was fertilized in a laboratory.

In scientific writing, ovum may be used for one egg and ova for more than one. In everyday medical communication, egg and eggs are more common and easier to understand.

A person is born with a large number of immature egg-containing structures called follicles. Over time, many naturally break down.

After puberty, hormonal signals may cause follicles to develop during menstrual cycles. Usually, one follicle becomes dominant and releases an egg, though ovulation does not occur in every cycle and more than one egg may occasionally be released.

It usually occurs during part of the menstrual cycle, but the exact timing varies. Stress, age, illness, hormonal conditions, medication, breastfeeding, and other factors may affect ovulation.

After release, the egg enters a fallopian tube. It remains capable of being fertilized for a relatively limited period, while sperm may survive longer within the reproductive tract.

Pregnancy is therefore possible from intercourse occurring before or near ovulation.

The resulting cell is called a zygote.

Fertilization commonly occurs in a fallopian tube. The zygote may then divide while moving toward the uterus. If it successfully implants in the uterine lining, pregnancy may continue.

Fertilization does not guarantee implantation, pregnancy, or live birth. Many biological steps must occur successfully.

If pregnancy does not occur, hormonal levels change and the uterine lining is shed. This produces menstruation.

The unfertilized egg is microscopic and usually breaks down before or during this process. A person generally cannot identify the egg within menstrual fluid.

Menstruation mainly consists of blood, uterine-lining tissue, mucus, and vaginal fluid.

Factors that may affect eggs include:

• age;
• hormonal conditions;
• ovarian disorders;
• genetics;
• chemotherapy or radiation;
• some medications;
• surgery;
• certain health conditions.

Fertility generally changes with age because both the number of available eggs and the likelihood of chromosomal irregularities change over time.

However, age alone cannot predict an individual person’s exact fertility.

Eggs are then collected through a medical procedure called egg retrieval. In a laboratory, eggs may be combined with sperm or injected with a single sperm.

If fertilization and development occur, an embryo may later be transferred to the uterus or frozen for future use.

Not every retrieved egg is mature, fertilizes successfully, or develops into an embryo.

A person may freeze eggs because of:

• planned medical treatment;
• concern about future fertility;
• delayed parenthood;
• gender-affirming treatment;
• personal circumstances.

Frozen eggs may later be thawed and used in fertility treatment.

Egg freezing may preserve reproductive possibilities, but it does not guarantee a future pregnancy or live birth.

Donated eggs may be used by:

• people whose ovaries do not produce usable eggs;
• people with certain genetic risks;
• older intended parents;
• male couples using a gestational carrier;
• some single intended parents.

Egg donation requires informed consent, medical screening, and clear agreements concerning privacy, compensation, storage, future use, and legal parenthood.

This risk is most closely associated with vaginal intercourse involving semen, but pregnancy may also be possible when fresh semen is transferred near the vaginal opening.

Activities such as kissing, masturbation performed alone, and oral sex do not cause pregnancy unless sperm is somehow transferred into the reproductive tract.

Contraception works by preventing ovulation, blocking sperm, reducing fertilization, or preventing other steps necessary for pregnancy.

During fertilization, it combines with a sperm that also usually contains 23 chromosomes. The resulting zygote normally has 46 chromosomes.

The egg also supplies much of the cellular material needed during the earliest stages of development, including mitochondria and nutrients.

The egg’s chromosome contribution helps determine genetic characteristics, but development is also influenced by genes from the sperm, pregnancy conditions, and many other biological factors.

A person with ovaries may identify as:

• a woman;
• a man;
• nonbinary;
• another gender.

Some transgender men and nonbinary people produce or preserve eggs. Hormone therapy, surgery, age, and health conditions may affect ovulation and fertility.

Anatomy, reproductive capacity, gender identity, and sexual orientation are separate concepts.

A person should understand:

• why eggs are being collected;
• how the procedure works;
• possible risks;
• how long eggs may be stored;
• who may authorize their use;
• what happens after death, separation, or withdrawal of consent;
• whether eggs may be donated, discarded, or used in research.

Reproductive material should never be used in ways that violate the provider’s informed agreement.

An egg is released during every menstrual cycle.
Some cycles occur without ovulation.

Fertilization guarantees pregnancy.
Implantation and continued development must also occur.

Egg freezing guarantees a future baby.
It preserves a possibility but cannot guarantee success.

Only women produce eggs.
Some transgender men and nonbinary people also have ovaries and may produce eggs.

An egg determines a person’s gender.
Reproductive cells do not define gender identity.

1. An egg is a reproductive cell usually produced in an ovary.
2. An egg may be released during ovulation.
3. A sperm cell may fertilize an egg in a fallopian tube.
4. A fertilized egg becomes a zygote.
5. An unfertilized egg is microscopic and usually breaks down naturally.
6. An egg may be collected and frozen for future fertility treatment.
7. A donated egg may help another person attempt pregnancy.
8. Producing an egg does not determine someone’s gender identity.
9. The use of an egg in fertility treatment requires informed consent.
10. Accurate discussion of egg should distinguish ovulation, fertilization, menstruation, fertility, gender, and pregnancy.

However, sexuality is broader than reproduction. Attraction, pleasure, intimacy, orientation, and sexual expression do not require fertilization or the production of eggs.

Accurate sexuality education explains how eggs develop, ovulate, and participate in fertilization while respecting bodily autonomy, gender diversity, informed reproductive choices, and consent concerning fertility treatment and reproductive material.