Variations in the thoracic duct of the Japanese monkey (Macaca fuscata)

Variations in the thoracic duct of Japanese monkeys were compared with previous reports on the human (Japanese) thoracic duct. The most striking difference between man and the Japanese monkey was that in the majority of the monkeys examined the right thoracic duct ascended without crossing to the left side whereas in man the upper portion of the right duct crosses over to the left. Although most thoracic ducts in man, other primates and domestic animals reportedly enter the left venous angle, about half of the ducts of Japanese monkeys enter the right venous angle. A ring configuration in the thoracic duct was found in 24.4% of Japanese monkeys. This was less frequent than human Japanese. Three out of 41 monkeys had an intercalated lymph node, situated between the 10th and 11th and 12th thoracic vertebrae; this has only occasionally been reported in man.