Conception happens when a sperm penetrates the waiting egg. It does this by releasing enzymes that help to break down the protective cells covering the egg.
Once the sperm has entered, the egg immediately closes its outer membrane to any other sperm that have made it this far.
Although this is the primary stage of conception officially this is the two weeks of pregnancy, and this fertilized egg is called a zygote.
Straight away, the zygote begins dividing into identical cells as it is swept down the fallopian tube. It attaches itself to the thickened lining of the womb where it will continue to grow and develop.
After that, the ball of cells in the womb has developed into an embryo. Although it’s only the size of a poppy seed, a lot is happening. Cells are migrating to an area known as the primitive streak, and forming into three layers that will later become baby’s organs and tissues:
In the top layer, a hollow structure called the neural tube begins to form. This is where the baby’s brain, backbone, spinal cord, and nerves will develop. Skin, hair, and nails will also develop from this layer.
The middle layer is where the skeleton and muscles grow, and where the heart and circulatory system will form.
The third layer houses the beginnings of what will become the lungs, the intestines, and the urinary system. The placenta is in the early stages of development.
The embryo is surrounded by an amniotic sac, which is filled with fluid to cushion and protect it. The placenta is in the early stages of development. Once it’s fully formed, at about 10 weeks, it will supply the baby with all the oxygen and nutrients requires. Until then, a small yolk sac provides all the nourishment the embryo needs.
