Rhododendrons and azaleas are arguably the Southâs favorite shrubs. Many people think of them as entirely different plants, but they both belong to the genus Rhododendron, which comprises more than 800 species and 10,000 named selections.
After fertilization, the zygote begins to divide rapidly. Twenty-four hours after fertilization, the zygote contains two cells, and three days after fertilization the zygote has 16 cells and is called a morula. The cells continue to divide and form a hollow bundle called a blastocyst. The blastocyst implants in the endometrium, and the cells begin to form the embryo. The embryo is present at five to six days after the zygote is fertilized. The embryo is a clump of cells inside the formerly hollow blastocyst, and is surrounded by the trophoblast.
The other sperm die within 48 hours. The fertilized egg is now called a zygote. The depolarization caused by sperm penetration results in one last round of division in the egg's nucleus, forming a pronucleus containing only one set of genetic information.The pronucleus from the egg merges with the nucleus from the sperm.Once the two pronuclei merge, cell division begins immediately. The dividing zygote gets pushed along the Fallopian tube. Approximately four days after fertilization, the zygote has about 100 cells and is called a blastocyst.When the blastocyst reaches the uterine lining, it floats for about two days and finally implants itself in the uterine wall around six days after fertilization.he pronucleus from the egg merges with the nucleus from the sperm. Once the two pronuclei merge, cell division begins immediately. The dividing zygote gets pushed along the Fallopian tube. Approximately four days after fertilization, the zygote has about 100 cells and is called a blastocyst.