Female Reproductive System: Structure and Processes
The Female Reproductive System
The female reproductive system is formed by the ovaries and reproductive tracts: the fallopian tubes, the uterus, the vagina, and the vulva.
Ovaries
They are the female reproductive gonads. Female gametes, or ova, are produced in the ovaries. The ovaries are two organs whose size and shape resemble that of an almond. In addition to producing female gametes, the ovaries produce sex hormones, estrogen and progesterone, which are essential for adequate sexual development and reproductive ability.
Fallopian Tubes
Also known as uterine tubes, these are two small tubes with a funnel-shaped opening located at the end, which is close to the ovaries.
Uterus
This is a frustoconical-shaped cavity in which the fallopian tubes end. Its wall is formed by a muscular layer. Inside, it has a mucous layer.
Vagina
This is an elastic tube. It has glands that secrete lubricating substances in order to facilitate penetration.
Vulva
This is the female external genital organ. It is composed of skin folds, including the clitoris, which is a very sensitive organ.
Oogenesis
Oogenesis is a cyclical process that brings about cyclical changes to the uterine mucus. This is why we distinguish between the uterine and ovarian cycles.
Follicular Phase
This lasts 14 days and takes place thanks to the follicle-stimulating hormone (FSH), produced by the hypophysis.
Ovulation
This consists of the release of an ovum through the ovary as a consequence of the production of the luteinizing hormone (LH) by the hypophysis.
Luteal Phase
Once the ovum is released, the corresponding area transforms into a mass of cells that produces and secretes the hormone progesterone.
Menstrual Phase or Period
This is considered the beginning of the cycle. Due to a sharp decrease in the ovary’s hormonal secretions, the thick mucus of the uterus breaks off and is released to the exterior along with blood from the blood vessels. The menstrual flow lasts about 4 to 5 days.
Proliferation Phase
The uterine mucus is reconstructed thanks to the action of the estrogens produced by the ovaries. This lasts approximately 11 days.
Secretory Phase
The lining of the uterus reaches its maximum thickness and is prepared to host and feed the fertilized ovum. It lasts about 12 days, when the production of the hormone ceases.
Fertilization
Fertilization takes place inside the female reproductive system, usually in the fallopian tubes. Every ejaculation (semen release) releases between 300 and 400 million sperm.
- What happens seven days after fertilization has occurred?
It arrives at the uterus and joins with the endometrium. - What is the name of the process?
The process is called nidation or implantation. - How long does gestation approximately take?
It lasts approximately 280 days, or 9 months. - What happens during the process?
The zygote transforms into a human being composed of 100 billion cells, which can form tissues and organs. - When does an embryo become a fetus?
The embryo takes on a human shape 2 or 3 months later. - What are the 3 stages of embryo development?
- Germinal: After a series of divisions, the zygote transforms into a cell mass known as a morula, that becomes hollow and creates another structure known as a blastula.
- Embryonic: Three layers of cells are formed from the blastula: the inner layer, the middle layer, and the outer layer.
- Fetal: In this stage, all body structures are formed, and the embryo becomes a fetus.
- What is the amnion?
The amnion fills up with amniotic fluid that protects the fetus from bumps and external pressures. - What is the placenta?
A membranous organ that is developed during the second month of gestation.
Childbirth
Dilation of the Cervix
This is the hardest stage of birth (lasting between 3 to 12 hours). This is known as”breaking water”
Fetus Release
This stage can last from 30 minutes to an hour. The fetus pushes its head out first; if this does not happen, the birth becomes more complicated, and on occasion, the fetus is extracted through a cesarean section.
Delivery of the Placenta
After the baby is born, the uterus suffers more contractions in order to release the placenta and umbilical cord. After this stage is finished, the birth ends.
Twins
Fraternal Twins
These originate from two ova that are fertilized by two different sperm. This happens when double ovulation occurs.
Identical Twins
These originate from a single zygote, which has divided itself into two cells that have separated, and thus each cell becomes an embryo.