Mammals, which include humans, give birth to live young as opposed to laying eggs like birds, reptiles, amphibians, many fish, and insects. Baby mammals develop in the wombs of their mothers. Another name for the womb is the uterus, a vital female reproductive organ.
Features
Pregnant mammals carry their developing babies inside their uterus. This organ is about 3 1/2 inches long prior to conception and weighs just under 3 ounces. The lower portion of the uterus is called the cervix, which has an opening called an os. The os dilates, or expands, to 10 centimeters in diameter during labor. This allows the head of the baby to push out of the uterus, through the birth canal, and out of the mother's body.
Function
Three layers make up the wall of the uterus. The outer wall is the serosa which contains fibers to support the organ. Next is the myometrium. This layer contracts during a woman's period to force the inner-most layer, the endometrium, to be expelled in a bloody discharge through the vagina. Each month a new endometrium layer forms and thickens so that if the woman conceives a child, it can receive the fertilized egg which must implant in the endometrium to survive.
Significance
The human uterus connects to each of the two ovaries by a fallopian tube. Girls are born with more than 400,000 eggs already stored in their ovaries. After she reaches puberty, once each month an egg is released into one of her fallopian tubes. Sexual intercourse releases male sperm cells into the woman's body, and conception may occur if the sperm and egg meet inside the fallopian tube. Then, stimulated by the hormone progesterone, the fertilized egg must travel to and implant in the endometrium that lines her uterus. If the fertilized egg does not reach the endometrium, an ectopic pregnancy inside the fallopian tube may result. Then, as the fertilized egg grows, the fallopian tube may ultimately rupture, which can cause infertility and even death for the woman.
Benefits
The uterus of a pregnant woman grows to contain more than just the developing baby, which is called the fetus. It also holds the amniotic fluid, in which the baby swims and is cushioned, as well as the umbilical cord through which the baby receives nutrition and excretes waste products. The umbilical cord connects the baby to the mother through the placenta, which is attached to the wall of the uterus.
Expert Insight
There are many serious health conditions like uterine cancer that can impact a woman's uterus. The surgical procedure that is done to remove the uterus is called a hysterectomy. Over 600,000 hysterectomies each year are performed in the United States, making it the second most common surgical procedure for women.
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