The egg cell — also known as the oocyte or ovum — is the female gamete (sperm are male gametes).The egg cell is a large human cell, is almost perfectly round and contains a great deal of cytoplasm.
The egg develops in one of the woman's two ovaries. Ovulation occurs when a mature egg is released from the ovary, travels down the fallopian tube and is available to be fertilized by a sperm.
When the oocyte is fertilized, it is capable of becoming an embryo, attaching to a woman's uterine lining and developing into a healthy pregnancy and live birth.
Scientists' understanding is that a woman is born with a finite supply of oocytes, and as a woman ages, her egg supply dwindles until she has no more. This is when she enters menopause.
Ovarian reserve is a term that refers to the quantity and quality of the eggs a woman has left. Egg quantity and quality declines in the mid 30s and then declines faster in the late 30s and 40s.
There are screening tests for ovarian reserve, which are required prior to freezing eggs. These tests may include:
- Day 3 follicle stimulating hormone (FSH) levels test
- Estradiol levels test
- Clomiphene challenge test
- Anti-Mullerian Hormone (AMH) levels test
- Ultrasound for an antral follicle count
These tests can help determine which ovarian stimulation protocol would be most effective so that fertility doctors could retrieve the most eggs possible.