The Difference Between an Oocyte and an Embryo – What Happens During Conception?

DoctorKnowing what happens during conception can help you to understand the fertility process, especially if you’re about to undergo an IVF Cycle.

Difference between an Oocyte and an Embryo


Oocyte is the medical name for a woman’s egg that has not been fertilized. While it is immature, the oocyte remains in a woman’s ovaries. Women are born with all of the oocytes that they’ll ever have. Typically, one oocyte is matured per month, gradually reducing a woman’s egg reserve. Once an oocyte is mature, it is released into the fallopian tube through a process known as ovulation. The oocyte will wait in the fallopian tube for 24 hours to be fertilized. After that point, the oocyte is no longer viable and will be reabsorbed by the body. If the oocyte is fertilized, it is now considered to be an embryo.


Embryos are fertilized oocytes. They are the result of an oocyte being fertilized with a single sperm. This can occur as a result of intercourse or during fertility treatment. Once the oocyte is fertilized it is deemed to be an embryo. Immediately, the embryo begins to develop. The number of cells contained in the embryo continually increases as the embryo matures. As the embryo develops it moves from the fallopian tubes to the uterus. Once it reaches the uterus, it implants in the uterine wall. The uterine wall ultimately provides nourishment to the embryo. Developments that occur during the embryonic phase include the formation of the fetus’ limbs, heart, brain, eyes, and eyelids.

Successful Conception Through Oocyte Fertilization and Embryo Transfer

For additional information about the phases of oocyte and embryo development – read more about a successful embryo transfer. Schedule your consultation with the fertility experts at New Hope Fertility Center. Please click the link below to enter your information and New Hope will contact you – or, simply call 917.525.5496.


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