The umbilical cord of an 8-10 week human foetus, the strand of tissue containing the 2 spiralling arteries that carry blood to the placenta (the organ embedded in the uterine wall that interfaces the foetal & maternal circulations, exchanging nourishment & waste products) & 1 vein that returns it to the foetus. The role of the placenta is complex, being more than a filtration or exchange system; it may be considered as a multi- organ system for the developing foetus. It also assists the mother's body functions by synthesising a range of steroid hormones, similar to those manufactured by the pituitary gland.