1. Menstrual Cycle Ovarian Cycle
Follicular Phase (Days 1-14): Follicle Stimulating Hormone (FSH) induces a few ovarian follicles to begin maturing and preparing to release an egg, they will compete for dominance, all but one will stop growing and the dominant one will continue to maturity
Ovulation (Day 15, on average): luteinizing hormone (LH) is secreted to trigger ovulation, the follicle ruptures and releases the oocyte (unfertilized egg) into the fallopian tube
Luteal Phase (Day 15-28): Begins with the formation of the corpus luteum from the ruptured follicle, which produces progesterone which suppresses LH and FSH to prevent the maturing and rupture of more follicles

2. Menstrual Cycle Uterine Cycle
Menstruation (Days 1-7): The uterine lining from the previous menstrual cycle breaks down and is expelled if the egg was not fertilized
Proliferative (Days 8- 14): The maturing follicles releases increasing amounts of estrogen causing the uterine lining to grow, or proliferate
Secretory (Days 15-28): corpus luteum is producing progesterone, which makes the thickened lining of the uterus receptive to the implantation of the blastocyst (produces embryo) and supporting early pregnancy by increasing blood flow to the uterus

3. Embryonic Development

4. Embryonic Development
Fertilization
The union of two zygotes, a sperm cell and an egg cell
Sperm penetrates outer layer of egg cell with digestive enzymes from the acrosome
The two nuclei fuse to create a nucleus with 46 chromosomes

5. Embryonic Development

6. Embryonic Development
First Trimester (Weeks 1-14)
In weeks 2-4, nutrients and waste is handled by the uterine lining until the placenta forms to act as a bridge between the embryo and mother
At 5 weeks, limb buds, eyes, heart and liver have been nearly fully formed (heartbeat can be seen in ultrasound)
Brain activity is detected in week 5 or 6
Embryo grows and at week 8, the term fetus applies since the body is fully formed
About 5 cm in length, many organs (liver, lungs) still aren’t functioning
Sex organs form during third month (weeks 9-12)

7. Embryonic Development
Second Trimester (Weeks 15-28)
Mother can detect movement of fetus at around week 20
All organs continue to grow and develop
Placenta has taken over the production of estrogen and progesterone from the corpus luteum, which disintegrates
Fetus is about a half pound and is 6 inches long

8. Embryonic Development
Third Trimester (Weeks 29-40)
Most rapid period of growth occurs and organ development continues until birth with some continuing after birth (nervous system and liver)
The fetus’s position changes moving its head down readying itself for birth and also to make breathing easier
Average weight is around 7.5 pounds

9. Embryonic Development

10. Embryonic Development
Birth
The baby’s new orientation causes the cervix to stretch, which sends a nerve impulse to the brain, a gland in the brain releases oxytocin, which then causes the muscle in the uterine wall to contract
Labour begins when the mother begins to experience these uterine contractions and is also marked by the dilation of the cervix
The cervix must dilate to 10 cm to allow the baby to pass, which can take a few hours

11. Embryonic Development
Stage 1: The amniotic sac bursts and the amniotic fluid escapes the uterus
Stage 2: The baby is then delivered from the uterus with the umbilical cord still attached
This stage is assisted by the mother pushing by compressing her abdominal muscles
Stage 3: The last stage is the passage of the placenta after the baby has been born and the organ has completely disengaged from the uterine wall, usually a few minutes after