In-vitro fertilization may soon become much more effective, if a new device dubbed the "silicone womb" comes out of testing successfully. Currently test-tube embryos are developed in an incubator, but the .2-inch long silicone womb, produced by Anecova, allows them to be implanted inside the mother for up to four days, during which time they're exposed to the uterus through 360 40-micron holes. The goal is to develop stronger, more resilient embryos for eventual pregnancy, but a small test in Belgium has so far proven inconclusive as to the device's effectiveness -- and some researchers doubt it'll work at all, since the embryos will be located in the uterus rather than the fallopian tubes where they would naturally develop. Still, there's hope that the environment inside the uterus will be an effective substitute -- to quote one researcher, "it's a lot closer to a fallopian tube than a plastic tray." 40 women are signed up for testing starting today, but results aren't expected for some time.