If you are a teen and pregnant, you probably have a lot of questions about what is happening to your body and what will happen to your body over the next several months. This article is intended as a basic overview.
Ovulation is the release of a mature egg from the follicle on the surface of the ovary. After the ovum is released, it is caught up by the fimbriae of the fallopian tube. Here wavelike peristaltic actions move the ovum down the fallopian tube toward the uterus. It usually takes an ovum about 5 days to pass through the fallopian tube. If sperm are present, fertilization occurs within the fallopian tube.
After the ovum has been released, the ruptured follicle enlarges, takes on a yellow fatty substance, and becomes the corpus luteum. The corpus luteum secretes the hormone progesterone during the second half of the menstrual cycle. This maintains the growth of the uterine lining in preparation for the fertilized egg. If the ovum is not fertilized the corpus luteum dies and the endometrium sloughs off as the menstrual flow.
During copulation, a man ejaculates approximately 100 million sperm cells into a woman's vagina. The sperm travel upward through the vagina, into the uterus, and on into the fallopian tube.
When a sperm penetrates the descending ovum, fertilization, also known as conception occurs and a new life begins. After fertilization occurs in the fallopian tube the fertilized egg, which is now called a zygote travels to the uterus.
Implantation is the embedding of the zygote into the endothelial lining of the uterus. From implantation through the eighth week of pregnancy the developing child is known as an embryo. A fetus is the developing child from the ninth week to the time of birth.
The Chorion and Placenta
The chorion is the outer membrane that encloses the fetus. It contributes to the formation of the placenta. The placenta is a temporary organ that forms with the uterus to allow the exchange of nutrients, oxygen, and waste products between the mother and child without allowing maternal blood and fetal blood to mix. The placenta also produces hormones necessary to maintain the pregnancy. At delivery the placenta is expelled as the afterbirth.
The amnion which is also known as the amniotic sac is the innermost of the membranes that surround the embryo in the uterus and forms the amniotic cavity. The amniotic fluid is the liquid in which the fetus floats and is protected. The umbilical cord is the structure that connects the fetus to the placenta. After birth the navel or the belly button, is formed where the umbilical cord was attached to the fetus.