A Brief Review of Female Anatomy

The vagina is an elastic canal, about four to five inches long. At the end of this canal, in the deepest recess of the vagina, is a structure called the cervix, which is the entrance to the womb, or uterus. The uterus is a hard, muscular, pear-shaped structure with a narrow, triangular cavity inside, so small that it would barely hold a teaspoonful of fluid (see figure below). Yet this is where the fertilized egg must implant itself and grow during the next nine months into a full-size baby. The uterus has a remarkable capacity to expand to allow room for the developing baby, pushing aside and squashing all the other organs of the mother’s abdomen. When the baby is ready to be born, the muscles of the uterus contract during labor to squeeze the baby out into the world.

Far back in the corners of the uterus, on each side, are microscopic canals through which the sperm must squeeze in order to reach the fallopian tube, where it may encounter an unfertilized egg. Once the egg has been fertilized, it will pass through the canal in the opposite direction to reach the uterus. These microscopic canals leading from the uterus into the fallopian tubes are only about one-seventieth of an inch in diameter (the size of a pinpoint). The fallopian tubes are four inches long and hang freely in the abdomen. They widen at the ends into large, flowerlike openings called fimbriae.

The ovaries are the organs that make the female’s eggs and sex hormones. They lie outside of the uterus and fallopian tubes. When an egg is extruded every month from the surface of one of the ovaries (ovulation, it is released freely into the abdominal cavity rather than directly into the tube. The fimbria then comes to life like an octopus tentacle and actively grasps the egg, pulling it into the fallopian tube. The tube swallows the egg, nourishes it before and during fertilization for there days, and then transports it into the uterus (see figure below).

While the male produces billions of sperm every week, the female matures only one of her existing eggs for ovulation each month. The ovaries mature and release about four hudred such eggs during the course of a woman’s lifetime. Generally, the most fertile eggs are released earlier in life, and of her limited supply of four hundred thousands, about one thousand eggs will die inexorably every month. Thus with advancing years, though a woman may still be able to get pregnant, she is much less fertile than she was in her youth.