The nasopalatine duct and the nasal floor cartilages in catarrhine primates.

The nasal floor structures in catarrhine primates have been studied on the basis of histological serial sections of older fetuses of Presbytis, Hylobates, Gorilla, Pan, Pongo and Homo. For outgroup comparisons, sections of the strepsirhine Daubentonia and the platyrrhine Callimico are presented; in these taxa the nasal floor cartilages are intimately connected not only with the nasopalatine duct (STENO) but also with the persisting vomeronasal organ (JACOBSON). Whereas the vomeronasal organ has disappeared as a functioning sensory organ in catarrhines (occasional embryonic vestiges are reported), the nasopalatine duct is retained in cercopithecoids, hylobatids and in Gorilla; in Pan, Pongo and Homo at least remnants of the duct and of the associated cartilages are preserved. The systematic meanings of these findings have been discussed.