When arguing with the other side about when life begins, you might hear the argument that “We don’t really know for sure when a sperm stops being a sperm, so do you people also want to save the sperm?” Luckily for us, this argument can be answered in the following way. From Ethika Politika:
In normal fertilization, many sperm penetrate the corona radiata of the ovum (a layer of follicle cells surrounding the ovum). Then, typically only one sperm will penetrate the zona pellucida (a film of glycoproteins surrounding the oocyte) and reach the oocyte. The sperm’s membrane then fuses with the actual membrane of the oocyte. This fusion triggers changes in the oocyte (or rather, what was the oocyte) so that (a) the membrane of this new cell undergoes a rapid polarization, and (b) a calcium wave is produced throughout the new cell’s cytoplasm so that the zona pellucida hardens over approximately 30 minutes and repels penetration by sperm. These facts indicate that what is living at this point is not an ovum.
Did you get all that? All it is saying is that only one sperm fully penetrates an egg (oocyte) and after this, there are changes to this “oocyte” that indicate that it is not an oocyte anymore. So, we are not saving the sperm: We are saving a different organism because at fertilization a sperm and an egg cease to exist. A whole new organism is present.
The article then goes on to explain newer techniques of in-vitro fertilization and how these newer techniques are raising questions as to when sperm and ovum cease to exist. Just because we do not know where the “line” is when sperm/ovum combine to form a zygote does not mean we ditch what we know; namely that a new life is created when a sperm and egg fuse. In-vitro fertilization cannot override basic biological principles.