194 Obstetrics and Gynecology Board Review •••
❍ When does the placenta become the major source of progesterone?
7 to 9 weeks.
❍ What serves as the precursor for the placental progesterone?
Maternal cholesterol.
❍ What enzyme activity is lacking in the placenta, limiting direct production of estrogen from cholesterol?
17 α-hydroxylase.
❍ What precursor is used to make estrogen in the placenta, and from what source?
Dehydroepiandrosterone (DHEA), from maternal and fetal adrenal glands.
❍ What other hormones are produced by placenta?
Neuropeptide Y Calcitonin Parathyroid hormone-related protein (PTHrP)
Prolactin Renin Placental growth hormone (PGH)
Estrogen Leptin Human placental lactogen (hPL)
ACTH Relaxin Growth hormone variant (hGHV)
Inhibin Activin Hypothalamic-like releasing hormones❍ What is hPL and what is its function?
Human placental lactogen; promotes lipolysis, decreases maternal insulin, promotes mammary differentiation, and
directs nutrients to the fetus.
❍ What is the name of the 10 to 30 lobes comprising the basal surface of a placenta?
Maternal cotyledons.
❍ What is an accessory lobe called?
Succenturiate lobe.
❍ What is its clinical significance?
5% to 6% incidence. Infection or postpartum hemorrhage may result if retained in utero.
❍ What is the zone of fibrinoid degeneration between the invading trophoblast and the decidua basalis?
Nitabuch layer.
❍ What are the fetal macrophages found within the chorionic villi called?
Hofbauer cells.