Fertilization • Also referred to as conception. • Union of an egg and sperm cell. • Fertilization takes place in the Fallopian Tube. • How many sperm cells does it take to fertilize and egg ? • 1 • Within seconds after fertilization the outside of the egg changes.
When the sperm and egg unite, they form a Zygote. • Within 36 hours, the zygote begins to divide while traveling through the fallopian tubes. • It takes 4 to 5 days for the zygote to reach the uterus. • No longer solid mass of cell. Now has become a Blastocyst; a hollow sphere. • Blastocyst attaches to wall of uterus. This is the process of implantation. • After implantation, blastocyst becomes and Embryo.
Pregnancy • Most common sign, missed menstrual period. • Menstruation stops because progesterone levels stay high. • Can be determined as soon as implantation occurs. • Human Chorionic gonadotropinis found in the blood of pregnant women.
The Embryo • The attachment holding the embryo to the wall of uterus develops into an organ called placenta. • About 25 days after fertilization, a cord called umbilical cord form between embryo and placenta. • Umbilical cord is the embryo’s lifeline. Blood vessels that carry oxygen and nutrients to embryo and waste away from embryo.
The Fetus • Between the 3rd and 6th month, the fetus will grow to about 11 inches and weigh up to 2 lbs. • “Kicking” shows the sign of skeletal and muscles development. • Between the 6th and 9th month the fetus continues to grow. • Average baby will be 20 inches and weigh about 7.5lbs.