Human (and some other primates') uterine teres ligament represents a mammalian developmental novelty

The primordia of the structures developing into the mammalian male cremaster sacs emerge as well in females fetuses. In most species the structures developing from these primordia in females remain inconspicuous: the so-called uterine teres ligament consisting of a slender part across the uterine broad ligament and a more or less developed bulbous structure at the site where this ligament inserts into the inguinal abdominal bottom. Not many data are available concerning the growth, development, or function of the uterine teres ligament. In humans--and also in other "higher" female primates--the uterine teres ligament is a major structure consisting mainly of smooth musculature. It is attached to the ventral aspect of the tubo-uterine junction. From there it courses across the uterine broad ligament and extends, retroperitoneally, to the inguinal region where it pierces through the inguinal canal to end in the tissues ventral of the pubic bones.

Analysis of the fetal development of the human uterine teres ligament, as compared with that of various other non-primate mammals, offers an explanation for its unusual anatomical condition. Evidence is conferred that, in human fetuses, there is no counterpart for the slender ligament across the broad ligament in other mammals. Instead, the homologue of the rudimentary bulbous structure in the abdominal bottom of non-primate females develops into a strong muscular structure which is directly connected to the (para-)menonephric duct wall.

It is concluded that the human uterine teres ligament is to be judged a structure different from that of other, non-primate, mammals. It is speculated that the unusual structure of the human teres ligament is related to one or more of the many unusual features of human uterine development: as a single organ (uterus simplex), with a position deep in the abdominal cavity below the pelvic brim, and far away from the posterior abdominal wall. The unusual anatomical position may require an unusual construction of the uterine suspensory apparatus of which the teres ligament is one component.