forth life from a frozen cauldron, but has become so commonplace that the
wonder of it has evaporated. In vitro fertilization (IVF) is no less
wondrous than a proposal of a colony of humans on Mars, even though it
happens over 60,000 times a year in the United States, and 350,000 times a
year throughout the world. In recent years, we have passed one million
live births in the United States from IVF, and almost 2 percent of all
American births are from IVF.^6
It can be easily argued that a “test tube” baby is a temporary, nine-
month implant, but surprising new findings show that all women may
harbor the cells of their babies through the process of fetomaternal
transfer, wherein fetal cells cross the uterine-placental barrier and form
“microchimeric” nests of fetal cells within the mother.^7 Previously
thought to be impossible, the transfer of the cells into the mother may
have positive, protective effects, but also may represent a threat to the
host. Whether naturally conceived or developed via IVF, fetuses are
capable of “living forever” within their mother, even if they are not
properly “matched” (which normally results in cellular rejection). In short,
the process of fetomaternal transfer may be an ancient phenomenon we are
only recently appreciating, but the new art of IVF may, for the first time,
allow completely foreign cells to inhabit a woman’s body (with no shared
genes between fetus and mother if the egg was donated from another
woman, as is common among older women undergoing IVF). The ultimate
expression of a biological implant (an embryo) may take decades before
we truly understand its biological consequences, but until then, the miracle
of creating life with glass pipettes, liquid growth medium, and frozen
storage chambers will remain a beatific phenomenon.
Plastic (or polymer) implants are made of organic polymers—most
commonly from petrochemicals (i.e., from petroleum)—that are
synthesized from chemical reactions to create molecules that are long
chains of repeating building blocks, like a chain of paperclips. The
assembled chain of simple structural units can be extremely long—
thousands of units—and the chains themselves can be made to link
together sideways, forming a block of polymers. Nature does have its own
polymers, like horn, hair, or cellulose,^8 but the ability to synthesize
plastics (through the process of polymerization) in the years following
World War II has led to revolutions in packaging, shipping, manufacturing,
clothing, and medicine.