Umbilical cord from and contains remnants of the yolk sac and allantois. It forms by the fifth week of development, replacing the yolk sac as the source of nutrients for the embryo. The cord is not directly connected to the mother's circulatory system, but instead joins the placenta, which transfers materials to and from the maternal blood without allowing direct mixing. The length of the umbilical cord is approximately equal to the crown-rump length of the fetus throughout pregnancy. The umbilical cord in a full term neonate is usually about 50 centimeters (20 in) long and about 2 centimeters (0.75 in) in
Confraternities of the Cord the faithful began to wear a cord in honour of Saint Thomas, to obtain the grace of purity through his intercession. In the 17th century, societies were formed at different universities, the student members of which wore a cord in honour of Saint Thomas, hoping through his intercession to be protected from the dangers to which youth is generally exposed. The first Confraternity of the Cord of Saint Thomas was erected at the Catholic University of Leuven by the Belgian Dominican friar Franciscus Deurweerders in 1649, and numbered among its members all the professors and students of the Faculty of