Establishment of pregnancy initiates a dynamic and predictable series of changes in the
uterus. In rodents, the trophectoderm of the blastocyst develops through the stage of an
ectoplacental cone to become the placenta. The inner cell mass becomes the fetus and its
associated extra-embryonic ectoderm and mesoderm. Maternal changes support
development of the conceptus. These begin in the uterine stroma, which undergoes a
process known as decidualization, and progress to include dilation and elongation of the …