Approximately a half million American women at any given time are infertile because of diseased or damaged Fallopian tubes.

An artificial Fallopian tube that would provide an alternative for these women is in the second stage of research at the University of Utah Health Sciences Center. The system has produced live baby mice in table-top experimentation and is ready now for testing in larger animals, said Dr. Stephen K. Hunter, a senior medical student and assistant research professor.Although the research is promising, it is five to 10 years from clinical application.

A small part of the body, the Fallopian tube is complex, Hunter said. Mature eggs released by the ovaries are swept into the tubes and moved through peristaltic action and the movement of cilia or small hairs. Fertilization normally occurs in the tube, where the conceptus is nourished through the first critical days before moving to the uterus.

The University of Utah experimental Fallopian tube consists of a sac that encapsulates the ovary and retains mature ova as they are released. A tube runs from the sac to the uterus, replacing the damaged tube. A small pump is attached to the system (at this point, an external pump is being used, but eventually a fully implantable pump, of which models are available, would be used). The pump would provide nutrients and motility for fertilized eggs.

The patient would be monitored for ovulation and then, in a sequence based on the natural process, sperm and nutrients would be introduced into the ovisac, utilizing the pump system, Hunter said. After fertilization is likely to have occurred, the pulsatile pump would flush the contents of the sac through the artificial tube and into the uterus at the optimal time for attachment to the uterine wall.

The concept has been tested in mice that were specially prepared for pregnancy. Ova harvested from mice were fertilized outside the body using the equipment and theory underlying the artificial Fallopian tube. The embryos were then implanted in the mice, Hunter said.

"We got normal, live offspring. We know we can achieve fertilization and float embryo down the tube and get living, viable offspring."

The next step will be to test the artificial Fallopian tube in a larger animal, probably sheep.

"I think there is a good chance of eliminating most cases of tubal infertility," Hunter said.

An artificial Fallopian tube would sidestep moral and legal questions that surround test-tube fertilization, including freezing embryos, and would hopefully produce a higher percentage of successful pregnancies, he believes.