Describe the germinal period, including the major developments that occur during this period

What will be an ideal response?

Answer: The germinal period lasts about two weeks, from fertilization and formation of the zygote until the tiny mass of cells drifts down and out of the fallopian tube and attaches itself to the wall of the uterus. The zygote's first cell duplication is long and drawn out; it is not complete until about 30 hours after conception. Gradually, new cells are added at a faster rate. By the fourth day, 60 to 70 cells exist that form a hollow, fluid-filled ball called a blastocyst. The cells on the inside of the blastocyst, called the embryonic disk, will become the new organism; the thin outer ring of cells, termed the trophoblast, will become the structures that provide protective covering and nourishment. Between the seventh and ninth days, implantation occurs: The blastocyst burrows deep into the uterine lining. Structures that feed and protect the developing organism begin to form—amnion, yolk sac, chorion, placenta, and umbilical cord. By the end of the germinal period, the developing organism has found food and shelter. Already, it is a complex being.