When performing the necropsy of newborn mammals there are three formations based on the umbilical cord, two caudal and one in the cranial direction. The two caudal formations are the two umbilical arteria, and the cranial one in the only umbilical vein.

Some days after birthday, the two umbilical arteria are retracted and round the urinary bladder, becoming the lateral suspensor ligaments of bladder. At the same way the umbilical vein is transformed and forms part of the round ligament of liver and in small proportion, known as Arancio conduct, becomes the venous ligament.

The two umbilical arteria, once have became ligaments, gave origin to the two primitive iliac arteries that are linked in cranial direction at the height of the vertebra L4, becoming the ascendant aorta. If both sides of the iliac arteria are observed we can find a lymphatic ganglions chain formed by two groups. The first is the right iliac side at the side of right primitive iliac arteria and the second is the left iliac side, placed at the side of the left primitive iliac arteria. Both lymphatic iliac groups are the start of the lumboaortic ganglion chain (4 or 5 pair of lumbar ganglions) going from the first lumbar vertebras to the aortic arch and beyond to the retro laryngitic ganglions.

This connexion between the two umbilical arteria and the two primitive iliac arteries with the first lumboaortic lymphatic ganglions is essential for the explanation of bacterial infections transmission (actinobacillosis) and virical ones (aujezky) from the sow to the piglets during pregnancy.

Finally point that this transmission way connects lumbar lymphatic ganglions chains with the ascendant transmission, od bacterial infections to the ganglion lymphatic system and in descendent direction of virical infections to the nervous system. This connexion way will be used later to explain the evolution of the “rope ladder” of annelids to nervous system and lymphatic system (both built by pairs of nervous or lymphatic ganglions)