Second, once penetrated by the sperm, the membrane becomes impermeable to penetration by other sperm. Fertilization — sperm union with the egg — occurs in this portion of the tube. MyChart Find a Doctor. The cervical mucus acts as a reservoir for extended sperm survival. Egg transport begins at ovulation and ends once the egg reaches the uterus.
At the end of this transition period, the embryo becomes a mass of very organized cells, called a blastocyst.
Conception: How It Works
Following penetration, a series of events set the stage for the first cell division. It's now believed that as women get older, this process of early embryo development is increasingly impaired due to diminishing egg quality. But the Izumo-Juno interaction is an essential first step without which fertilisation cannot occur. Accessibility links Skip to article Skip to navigation. This could lead to a new and novel non-hormonal contraceptive for both humans and other species of mammals. This is an increasingly popular method of IVF which involves injecting a sperm directly into an egg. MyChart Find a Doctor.