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The sperm and ovum combine to create a zygote. This happens in the fallopian tube.
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At this point, the zygote has divided into a ball of cells which can be grouped into an inner core and an outer shell. The inner core will continue to develop into the feotus itself, while the outer shell will form membranes that will nourish the feotus. This is called a blastocyst. This is made from around a hundred cells.
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The blastocyst implants into the endometrial lining of the uterus. (it will have left the fallopian tubes at this point.)
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Blastocyst becomes embryo. Meaning cells have started to differentiate into specialised tissue cells.
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The yolk sac serves as the source of nutrition for the feotus. It is the primative form of the curculatory system. It is essential as it is a replacement for internal circulation. WEEK 2
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The brain, spinal chord, heart and the gastrointestinal tract starts to develop. WEEK 3
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Limb buds are visible. WEEK 4-5
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Eyes and ears begin to form.
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The brain develops into five areas and some cranial nerves are visible. WEEK 4-5
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The heard continues forming and now starts beating. Blood moving through main vessels. WEEK 4-5
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Lungs begin to form
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The arms and legs have grown longer, and foot and hand areas can be distinguished. The hands and feet have fingers and toes (digits), but may still be webbed. WEEK 6
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WEEK 7
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Facial Features Continue to develop and ear ridge nearly finished forming. WEEK 8
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No longer considered an ambryo, but is called a feotus.
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Red blood cells are produced in the liver. WEEK 9-12
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Genitals appear well differentiated.
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The baby can make a fist with its fingers.
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The baby begins to make active movements, including sucking its mouth. WEEK 13-16
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The baby can hear
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The mother can feel the feotus move.
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Hair covers entire body, and eyelashes and eyebrows form.
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Nails form on toes and fingers.
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Bone marrow begins to make blood cells. WEEK 20-22
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Baby satrts storing fat. WEEK 21-23
