A single umbilical artery in the baboon

Single umbilical arteries were found in the cord of a newborn baboon, a two month old fetus and a 30 d baboon embryo. This anomaly is frequently reported in humans and often associated with gross physical malformations. No obvious malformations were noted in the cases reported here. A number of etiological factors may produce this condition. The involution and obliteration of one artery or the hypertrophy and elongation of an anastomosis between embryonic arteries are two possible processes in the development of this condition.