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Subscribers log in here  Placental development and physiology
Development of the placenta is a highly regulated process that
is essential for normal fetal growth and development, and for
maintenance of a healthy pregnancy. The placenta fulfills
several critical roles as the interface between mother and
fetus: it prevents rejection of the fetal allograft, enables
respiratory gas exchange, transports nutrients, eliminates fetal
waste products, and secretes peptide and steroid hormones.
Implantation and invasion — Development of the placenta and
fetus is a continuous process that begins at the time of
fertilization. The first three days of development occur within
the fallopian tube. Four days after fertilization, the morula (a
solid mass of blastomere cells) enters the uterus. On the fifth
day after fertilization, the morula bec