Akademik Veri Yönetim Sistemi
INSAC World Health Sciences, Doç. Dr. Mehmet DALKILIÇ Dr. Öğretim Üyesi Hale KÖKSOY, Editör, Gece Kitaplığı, Ankara, ss.940-961, 2022
The term chimera is used to describe a being composed
of parts from different sources or living beings that emerged or were created as a mixture of different living things. The genetic
chimera describes a mixed organism consisting of two or more different
zygotes. Often during pregnancy, a reciprocal exchange
of cells occurs between the mother and the fetus, including
some cells of the immune system. These pluripotent cells cross the placental barrier and enter the host's
body, can settle in different organs and survive
for decades. Thus, an individual may have a small population of foreign
cells and hence nucleic acids of another
genetically different individual. This phenomenon is known as microchimerism (Mc). The physiological consequences of Mc are not clear. However,
it can be said that it
may have beneficial or harmful effects or have no effect at all. Cases of chimerism are generally classified into
three categories; 1. occurring after a blood
or bone marrow transplant (artificial); 2. formed by the fertilization of two oocytes by two spermatozoa and the development of the organism
(tetragametic); 3. routine stem cell transfer between mother and fetus
during pregnancy. The most common
known form of microchimerism (Mc) is cell transfer
that occurs during pregnancy; transfer of the baby's stem cells to the mother (fetal microchimerism=FMc) and the
transfer of the mother's stem cells
to the baby (maternal microchimerism=MMc). Fetal and maternal cell exchanges
are quite common during pregnancy. Now, we know that
the placenta is not an
immunologically inert barrier, but rather, it allows the reciprocal transport of maternal and fetal cells in a state of
mutual tolerance during gestation. To
develop microchimerism, it is not
also necessary to continue
a pregnancy and deliver an infant. Surgical
and spontaneous abortions can deliver up to 500,000 nucleated fetal cells into a woman's
circulation (1).