The labyrinth in mouse is derived from the trophectoderm of the early embryo and is part of the extraembryonic tissues. It's not derived from maternal tissues. The labyrinth does have a cavity into which maternally-derived blood from the spiral arteries flows through trophoblast-lined “canals” that carry maternal blood to the base of the placenta for exchange with fetal blood.
Human placentas are structurally different.
Howard Dene wrote:
> Hi Cindy,
> I am sending this as an e-mail because I am not proposing any MP terms
> or MP re-arrangement at the moment.
> The placenta is a complex structure with both maternal and embryonic
> components. Currently terms related to the placenta are found only
> under embryogenesis. I would be inclined to argue however, that
> maternal structures such as the labyrinth could be considered part of
> the reproductive phenotype of the mother rather than an embryogenesis
> phenotype of the embryo. Certainly the maternal placenta can be
> expected to influence phenotypes such as litter size, gestation length,
> spontaneous abortion rate, and other similar phenotypes that we do
> consider maternal phenotypes. Just a thought -- I am annotating a
> paper on Il10 knockouts where the phenotype is cross-sectional area of
> the placental labyrinth. The important genotype (I think) is that of
> the mother, not the embryo but I will be annotating to embryogenesis terms.