Fetal membranes, umbilical cord and placenta Dr. Sanjaya Adikari Department of Anatomy

Objectives Describe the structure and function of the placenta, umbilical cord and membranes

Chorionic plate Decidual plate

Chorionic villi Lacunar/intervillous spaces Cotyledon (15-20)

Macroscopic appearance of placenta

Placenta – fetal surface

Placenta – maternal surface

Placenta and membranes

What is placental barrier?

2 1 Placental barrier

Blastocyst

Functions of the placenta Exchange of gases Removal of metabolic products Nutrition Transmission of maternal Ab Production of hormones

Placental hormones Human chorionic gonadotropin-hCG Progesterone Oestrogens Human chorionic somatomammotropin-hCS Relaxin These are secreted into the maternal circulation. Most maternal hormones do not cross the placenta.

Weeks hCG 612 Maintains the corpus luteum during the initial period of pregnancy Progesterone Oestriol Maintains the pregnancy Relaxin Inhibits myometrial contractions hCS Lactogenic function Growth stimulation

Weeks hCG 612 Progesterone Oestriol Relaxin hCS

Unwanted functions of placenta Transfer of infectious agents Transfer of drugs

Functions of the fetal membranes Protection/shock absorption

Umbilical cord umbilical arteries umbilical vein Wharton’s jelly

References Review of medical physiology by William F. Ganong Medical embryology by Jan Langman