Week 1 Assignment: The Sperm and the Egg
Nathaniel Morris
PSY/265
3/18/2012
Nicole Pansey
Week 1 Assignment: The Sperm and the Egg Many of us have heard about the birds and the bees. Most parents find this story to better illustrate how conception happens. When a young child asks their parent “Where do babies come from”, a parent may find it hard to look in their young child’s eyes, and describe exactly what happens. The actual scientific process may be harder to explain, but will be more useful for the child when they get older. It would probably be more effective with a variety of visual aids, and preparation in order to present this to an adolescent. Deciding at what age to tell your child the scientific version should depend on the parent. The “birds and bees story” may be more appropriate for a younger child, and the scientific version can be more explained when they are a little more mature. A girl should know about the sexual reproductive system when she starts menstruating. If she is not taught properly, she may not understand what is going on with her body, and may wind up pregnant at an early age. In order to explain the scientific version, first, you would have to start out by explaining the immediate male and female body parts that are involved; the penis and vagina. The inner part of the vagina consists of two ovaries, the cervix, and the uterus that are all connected to the uterus by the fallopian tubes. These are all structures that make up the woman’s reproductive system. A female is born with all the ova she will need for her entire life, which adds up to about 2 million. Due to a lot of the ova being immature in form, only about 400,000 actually make it into puberty. “During a woman’s reproductive years, from puberty to menopause, only 400 or so ripened ova, typically 1 per month, will be released by their follicles for possible fertilization.” (Rathus, S. A., Nevid, J.S., and Fichner-Rathus, L. 2005). Because a woman produces so little eggs (and while still a fetus) it is still a mystery how an egg chooses to be fertilized. An egg starts out in the woman’s ovaries. The ovaries are also responsible for the production of estrogen and proestrogen. Eggs are fertilized in the fallopian tubes, and since sperm can live up to five days in a woman’s uterus, it could explain why women can get pregnant over several days each month based on when she ovulates. An egg, however, does have a more time-sensitive schedule. The egg is only fertile for about 12 to 24 hours after it leaves the ovary. With males, the sexual reproduction system is mostly external, and includes; the penis and the scrotum. The penis has three cylinders of spongy material that run the length of the penis. During sexual arousal, these cylinders are filled with blood and cause an “erection”. When an orgasm has been reached, the penis secrets semen through a urethral opening, also called the urethral meatus. The internal sex organs of a male include; the testes, which are inside of the scrotum. “The scrotum is a pouch of loose skin that becomes covered lightly with hair at puberty. It has two compartments that hold the testes.” (Rathus, S. A., Nevid, J. S., & Fincher-Rathus, L. 2005). Both testicles are held in place by their own spermatic cord, which is the structure that contains the cremaster muscle, nerves and blood vessels, and the vas deferens. The testes are responsible for producing germ cells (or what we call in this instance; sperm), and sex hormones. The production of a mature sperm takes about two months and in takes place starting out in the seminiferous tubules (testes). Once the sperm is matured enough, it moves to the epididymis waiting for the release that moves them through the urethra. While moving through the urethra, the sperm is combined with a substance that helps the sperm and their long journey to the egg. Unlike the woman who is born with all the eggs she will ever produce, the male’s sperm count seems endless. It is said that a man can produce enough sperm in 10 to 20 ejaculations to populate Earth. A girl cannot conceive a baby without engaging in coitus first. Once the penis is inserted into the vagina, intercourse occurs. The “introitus” (also known as the vaginal opening) is the only visible part of the vagina, and during coitus the penis stays inside the vagina cavity. It continues until sperm is secreted. Once sperm is released into the vaginal cavity, the little fellows sure have a long road ahead of them, and most never make it. They start to propel themselves by whipping their tales starting before they are ejaculated from the penis. Once they start, they continue on through the cervix and into the uterus where the fallopian tubes are. The journey of the sperm through the fallopian tubes is about six to seven inches, but can take several hours to accomplish. When the sperm enters the body, it starts going through a changing process because of the substances found in the woman’s cervix. A sperm is not fully mature until they go through the “capacitated” process. The egg has already gone through the dynamic process of ovulation and is just sitting there waiting on the sperm to fertilize it. Once the sperm reaches the egg, mitochondria (sperm energy) propels the sperm, and about 100 of his friends have made it to the eggs “outer wall” so far. The sperm begins to drill the outer layer with their tiny heads, and beating the walls with their tails, causing the egg to rotate counterclockwise. At this time the egg is still covered in a sheath of nutrient cells that the sperm must break through. Once the cap of the sperm disappears into the first layers, it releases enzymes that help the egg wall to become more vulnerable so it can penetrate. Once the sperm infiltrates the inner cell of plasma, the egg is overtaken by a chemical composition that changes it. This process automatically shuts out all the other sperm, even if they have almost pierced through. The sperm still has a way to go before the fertilization process is complete. The sperm begins to work like a revolving drill, with the head rotating due to the tail movements. Once the sperm inserts its entire head passing through the ovum wall it penetrates the eggs plasma, and steadily heads towards the genetic material which is stored deep inside the egg. Both the sperm and the eggs’ nuclei are drawn toward each other and soon fuse. Once they have fused together, instantly there are numerous hereditary characteristics of a new individual that are determined. The reproduction process has finally occurred!

Reference Rathus, S. A., Nevid, J. S., & Fincher-Rathus, L. (2005). Human Sexuality in a world of diversity (6th ed.). Boston, MA: Allyn and Bacon. References
Rathus, S. A., Nevid, J.S., and Fichner-Rathus, L. (2005). Human sexuality in a world of diversity. (6th ed.)Ch.1.Pg1-10. Boston: Allyn and Bacon.