The title of the article you posted was "Existence of Microchimerism in Pregnant Women Carrying a Boy!" What part of "women" isn't clear to you? Any Y chromosome cells aren't native to the woman.Does this also include women who have given birth to sons? Microchimerism among women who have given birth is quite common.
snippet:Existence of Microchimerism in Pregnant Women Carrying a Boy!
www.ncbi.nlm.nih.gov
A recent study proposes that women approximately at all times obtain fetal cells when they get pregnant. These have been noticed in the beginning of seven weeks of pregnancy. Later, the cells can be disappeared, though the cells may stay for a lifetime. Chan et al. reported that Y chromosomes were present in the brains of 63 percent of 59 deceased older women. Several researches evaluated the cells left behind by sons regarding fetal microchimerism, due to ease for its discrimination from the cells of their mothers (5)