Well, we learn today that there might be another way of starting the baby-building process, with no need for a female egg. Now, don't get me wrong. A male/female person who wants to become the father/mother of a baby still needs to get a little help from a friend. More precisely, from the girl who's going to carry the fœtus in her womb for nine months. But this lady doesn't collaborate initially by donating an egg, and she will therefore not be a parent of the future child.
Let's examine this gestation that doesn't start with a female egg. We might use a skin cell, from either a male or a female.
To simplify the graphical presentation, we show merely eight chromosomes. To start the process, half of the cell's chromosomes are removed: four. In the next step, the halved cell receives a male sperm.
At this point in my description of the process of babies whose gestation doesn't start with an egg, I'm reminded of a joke about an inspired inventor who's creating a miraculous aircraft. "It looks fabulous, with its swept-back wings and narrow tubular fuselage. And its jet engines are designed to take it rapidly up beyond the speed of sound. There's just a single problem that I still have to solve. How do I get the bastard to fly?"
That's where we are with our bundle of four chromosomes and a sperm cell in the above illustration. Without going into details, let's say that the group of biologists who've announced this new process claim that a simple cell formed by a sperm injected into half the chromosomes of a skin cell can indeed be made to evolve into an embryo. But how? Well, the biologists who are promoting this idea have published an article revealing how they were able to bring about the birth of healthy mice. A little imagination and faith is then required in order to see how a human male or female might get together with a male sperm-donor to build a baby. In fact, my dear Watson, it's rather elementary...