12 most iconic rivers on Earth. The Yangtze River's most famous sites include the incredible Three Gorges and the gargantuan Three Gorges Dam. There's a reason you know the names of these rivers--the Nile, the Mississippi, the Amazon--they've inspired exploration, legend, religion. Discover the waterways that shaped the world--and the cruises that reveal their secrets.
Illustration depicting ovulation and fertilization. Human fertilization is the union of a human egg and sperm, usually occurring in the ampulla of the uterine tube. The result of this union is the production of a zygote cell, or fertilized egg, initiating prenatal development.Scientists discovered the dynamics of human fertilization in the nineteenth century.The process of fertilization involves a sperm fusing with an ovum.he result of this union is the production of a zygote cell, or fertilized egg, initiating prenatal development. Scientists discovered the dynamics of human fertilization in the nineteenth century. The process of fertilization involves a sperm fusing with an ovum.
A blighted ovum (also known as âanembryonic pregnancyâ) happens when a fertilized egg attaches itself to the uterine wall, but the embryo does not develop. Cells develop to form the pregnancy sac, but not the embryo itself.A blighted ovum occurs within the first trimester, often before a woman knows she is pregnant. A high level of chromosome abnormalities usually causes a womanâs body to naturally miscarry.ells develop to form the pregnancy sac, but not the embryo itself. A blighted ovum occurs within the first trimester, often before a woman knows she is pregnant. A high level of chromosome abnormalities usually causes a womanâs body to naturally miscarry.