We must, however, draw attention to an important issue
regarding vitamin E level affecting spontaneous decidualization in
this particular model. It was clear that our rats sterile, perhaps
because spontaneous decidualization may be harmful to rats. Two
types of homeostasis are required to induce spontaneous decidualization,
VED and the application of exogenous estrogen, and it is
evident that both of these are harmful to pregnant rats. On the
other hand, the type of homeostasis that induces spontaneous
decidualization in humans does not negatively impact pregnancy.
This brings into question why humans, but not rats, can tolerate the
type of homeostasis that induces spontaneous decidualization. We
believe that this is related to differences in implantation depth in
rodents and higher primates. The diversity between these two
classes of species may thus be related to inherent differences in the
degree of invasiveness during placentation and will require further
exploration.