Editorial

Doctors believe they hove found o way to fertilise on egg with cells from any port of the body. rather than sperm. An Australian team has created embryos in this way with mice.

The research, which complement efforts to enable infertile women to "re program me" donated eggs with their Own genetic recipe, was originally intended to help couples to have babies that ore their own genetic offspring, even when the man has no sperm or even sperm-making cells.

This kind of researchers, in theory at least, can enable a lesbian couple to hove o baby, with one woman contributing an egg are the second a cell to fertilise it.

There are theoretical problems lo overcome in combining the genes of two women, because aspects of development ore controlled by a paternal gene, when a maternal copy is turned off, and vice versa, as a result of a process called imprinting.    

This is remarkable because, unlike sperm, the body cell has two sets of chromosomes. To overcome that problem, the team exploited cellular machinery t hat is used by an unfertilised egg to eject a spare set of chromosomes when it encounters sperm.

During normal fertilisation, two sets of chromosomes in on egg are separated and one set is ejected in o package that biologists call thy polar body, leaving o single set to combine with another set from the sperm.

After "fertilisation" of the mouse egg, the team used chemicals to persuade the egg to carry out the steps typical of normal fertilization: it released its spore set of chromosomes into a polar body; only this time the body cell also expelled its spare set into a second polar body.                                

In this way the team ended up with two polar bodies and :fertilised egg, with one set of chromosomes from the mother one the second from the adult cell. This is similar to an embryo derives from fertilisation by sperm.

The embryos go on to develop relatively normally in the laboratory and the team is about to transfer the embryos into the womb of surrogate mice.

Once offspring from animals hove been born, the team will test their genetics and behaviour and their ability to reproduce or; give birth to healthy offspring for o few generations. Only then can the technique be examined in the human.

These ore extraordinarily interesting experimenls. But the issue of increasing importance with all these kinds of developments it whether genes ore expressed [used] correctly after fertilization. This question leads us to another big question • Are genetically modified babies inevitable?