Interspecific pregnancy
Strictly, interspecific pregnancy is also distinguished from endoparasitism, where parasite offspring grow inside the organism of another species, not necessarily in the womb.
Potential applications include carrying human fetuses to term as a potential yet ethically controversial alternative to human surrogate mothers or artificial uteri for gay male couples,[3] mothers with damaged uteri or heterosexual couples that do not want to risk childbirth.
[3] For animals, it could be a valuable tool in preservation programs of endangered species, providing a method of ex situ conservation.
[5] Through this research, we gained a lot of knowledge about interspecific pregnancy, specifically what causes it to succeed and fail.
These immunological influences include: trophoblast (cells formed on the outer layer of a blastocyst (which provides nutrients to an embryo), rejection due to a cell-mediated immunological response, inappropriate interactions between trophoblasts and endometrium (site where blastocysts are implanted or the uterine lining), etc.
[10] However, other mice experiments indicate that an immune response towards xeno-fetuses does not belong to classical cytotoxic T lymphocyte or natural killer cell pathways.
[8] Due to their high importance, trophoblasts play a key role in interspecific pregnancy success.
[8] For example, the placental glycosylation pattern at the fetomaternal interface should optimally be similar to that of the host species.
[1][6] Methods to artificially stimulate gestational immune tolerance towards a xeno-fetus include intercurrently introducing a component of a normal allogeneic pregnancy.
[17] It has been theorized that the allogeneic component prevents the production of maternal lymphocytes and cytotoxic anti-fetal antibodies, but the mechanism remains uncertain.
Pre-transfer immunization with antigens from the species providing the embryo has promoted more rapid and uniform failure of the interspecies pregnancy in mice,[11] but increased survival in horse-donkey experiments.
[18] Embryos may be created by in vitro fertilization (IVF) with gametes from a male and female of the species to be reproduced.
