Subject: RE: fallopian tube blockages

Message: Always wondered about this. If medical science was able to come up with heart bypass surgery, why have they not tried to use a similar method to 'bypass' blocked tubes of woman who want to become pregnant?

Answer:
Mainly the problem has to do with the specialized structures of the fallopian tubes, and how they function. Unlike the comparatively large blood vessels of the heart, the tubes are very much smaller in diameter. Also, the tubes have specialized sections that accomplish a variety of functions while they transport a tiny ovum (egg) from the ovary to the uterus.

The end of the tubes near the ovary are funnel-shaped (infundibulum) with hundreds of nearly microscopic 'tentacles' that catch the (unfertilized) egg. During ovulation, the 'tentacles' exhibit a motion, causing the egg to enter into the tube. If this funnel-shaped end is badly damaged, fertilization -- later down the tube --- is unlikely.

The next, mid-section is about half the tube, and called the ampulla. The egg is pushed along inside the tube by a combination of mucous-producing and ciliated (hairy) cells, and contraction motions of the tube. This mid-section is where sperm meets and fertilizes egg.

Finally, the now-fertilized egg is pushed along toward a very much narrowed part of the tube (called the "isthmus"), approaching the uterus. The point at which the tube joins the uterus, the inside diameter of the tube is less than 1 millimeter (1/25 of an inch). To get through this opening, the ovum must shed an outer layer of cells (called, granulosa cells).

ALL of the above specialized functions of the fallopian tube are under hormone control. That is, the cells making up the different sections of the tube change how they behave, depending on the presence and amounts of female hormones which keep changing during the 28-day cycles that produces ovulation.

Seemingly, only another tube can be used to replace or bypass a fallopian tube. This would be unlike heart bypass surgery in which leg veins can be used to substitute for blocked coronary arteries. Leg veins are large, tough, and not so highly specialized as are the fallopian tubes; relatively thin, not very tough, and very highly specialized.

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F. Sweet, Ph.D.
Professor