Chorionic gonadotropin in the placenta of a chimpanzee (Pan troglodytes).

Chorionic gonadotrophin (CG) concentration in the 'near term' chimpanzee placenta was similar to that of human term placentae and significantly (p smaller than 0.05) higher than that found in term placentae of marmosets and rhesus monekys. A significant linear relationship, correlation coefficient r equals +0.999, was found between log mean placental weight and log mean CG concentration in placentae from marmosets, rhesus monekys and the chimpanzee.