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Ask most people what they know about the mechanics of sexual reproduction and you are likely to get anything from a reproachful sneer to a dirty joke. Most of us have been told at some time or another that the sperm meets the egg and ultimately a baby is produced. The dynamics of what really takes place, however, is so incredibly complex that John Medina’s book The Outer Limits of Life (1991, Oliver-Nelson Books, Nashville) consumes 282 pages in just generally describing the process.
The human sperm consists of a head and a tail. The head contains two parts, one part being the nucleus which contains the genetic information for the father’s part of the genetic makeup of the child. No further information is needed for the sperm to do its task (there is no messenger RNA). Unlike most cell nuclei, there are no holes (called nuclear pores) for communication with the outside world. The sperm is singularly programmed to do its job.
The second part of the head of the sperm is called the acrosome. The acrosome is the part of the sperm that enables penetration of the egg. This is done by enzymes that can digest proteins, sugars, and the materials of which the outside of the egg is made. The tail of the sperm has a mid-section that contains tiny energy sources called mitochondria. The remainder of the tail looks like uncooked spaghetti noodles. These “noodles” slide and ratchet past each other, giving a wiggling and writhing motion that causes the head of the sperm to rotate 180° every time there is motion in the tail and moves the sperm along at a rate of about five inches per hour.
The joining of the sperm and the egg is called “one of God’s greatest miracles” by Medina (page 87). As the sperm finds the egg, it encounters an object which is as much larger than the sperm is as a basketball compares to a paper clip. The sperm must first of all penetrate the thick outer layer of the egg called the zona pellucida which contains protein that enables the sperm’s outer protein to fit into it. The egg’s protein (called ZP3) prevents sperm from other animals from entering the egg. If the ZP3 is removed, sperm from other animals can fertilize the egg. There is also sugar in the ZP3 which the sperm digests. When this happens, the acrosomal section of the head of the sperm dumps its enzymes on the zona pellucida and a hole is opened up into the egg. The head and tail of the sperm minus the nucleus is then digested by the egg with the sperm’s nucleus left floaing in the egg’s cytoplasm.
Remember that thousands of sperm are trying to do this all at once. When a sperm’s nucleus enters the egg, three things are done within seconds to prevent any other sperm from putting its nucleus inside the egg. First, an electrical change occurs in the membrane of the egg. Second, the egg makes a change in the zona pellucida that hardens it into a form of cement, and finally a chemical that consumes sugar is released, stopping the sperm from attaching to the outside of the egg. All of this is just the starting point for conception. We have left out hundreds of details, not all of which is understood. Now the nine-month (plus) process that will culminate in a baby ready to live in the outside world begins.
David said in Psalm 139, “I will praise thee; for I am fearfully and wonderfully made.” Just a superficial understanding of what happens in the complex process of sexual reproduction should convince us of the impossibility of explaining all of this by chance. God has designed a system that is so successful that man now must learn to use it wisely so as not to strain the resources of all kinds available to him.

—John Clayton, Dandy Designs, May/June, 1995


Cora Gail Trent
www.cgtrent.com
cgtrent@att.net