[Phylogenetic aspects of the Jacobson's organ and nasopalatine duct topography in insectivores, primates, Tupaia and Didelphis].

A comparative study was made of the anatomy of the skeletal structures of Jacobson's organs and the nasopalatine ducts in insectivores, primates, Tupaia and Didelphis. The adult animals investigated can be devided in 2 groups according to the topography of this region. Each group has its characteristic structures. Tupaia, although a member of the eutherian mammals, shows striking similarities to the marsupial Didelphis. The structure of the nasal region of both points towards an ancestral origin. The organ of Jacobson of those primates and insectivores which were studied, are quite different with respect to the anatomy of these skeletal structures. Closest similarities within these both orders are found in Erinaceus and primates. The other insectivores studied, Talpa and the shrews, differ from them in so far as their cartilages of the corresponding region are for the most part ossificated. It seems that this nasal part is of value in revealing early phylogenetic relations.