Ontogenetic characteristics of the vomeronasal organ inSaguinus geoffroyiandLeontopithecus rosalia, with comparisons to other primates

Abstract

It has been suggested that the variability of the primate vomeronasal organ (VNO) may be greater than previously thought, especially among New World monkeys. It is not clear to what extent VNO variation reflects ontogenetic, functional, or phylogenetic differences among primates. The present study investigated VNO anatomy in an ontogenetic series of two genera of callitrichid primates, in order to assess recent attempts to develop VNO character states and to examine the evidence for VNO functionality at different life stages. A sample of six Leontopithecus rosalia, one L. chrysomelas, and six Saguinus geoffroyi was serially sectioned and stained using various methods. Two adult Callithrix jacchus were also sectioned for comparative purposes. The VNO of each primate was examined by light microscopy along its entire rostrocaudal extent. VNOs of the tamarins were described to determine whether they fit into 1 of 3 character states recently attributed to various New World monkeys. At birth, the two species of tamarins differed in the nature of communication between the VNO and nasopalatine duct (NPD). Two of 3 neonatal S. geoffroyi exhibited a fused VNO duct in a more dorsal position (adjacent to the nasal cavity) compared to that of L. rosalia. The VNO duct communicated with the NPD and was patent in neonatal L. rosalia. Both species appeared to have an age-related increase in the amount of sensory epithelium in the VNO. Subadult L. rosalia had caudal regions of the VNO that were exceptionally well-developed, similar to those of strepsirhine primates. Compared to subadults, all adult callitrichids appeared to have more ventral communications of the VNO duct directly into the NPD. Adult S. geoffroyi and L. chrysomelas both had VNO sensory epithelium separated by multiple patches of nonsensory epithelium. This contrasted with the VNOs of C. jacchus, which had a nearly continuous distribution of receptors on all surfaces of the VNO. The findings indicate that tamarins have delayed maturation of the VNO epithelium, and that some species have little or no perinatal function. These results also suggest that ontogenetic changes in craniofacial form may alter the position of the VNO in tamarins. The present study supports the use of at least two character states to categorize the VNO of various callitrichids, but it is suggested that one of these, previously called "reduced sensory epithelium" should be instead termed "interrupted sensory epithelium." The distribution of VNO sensory epithelium does not appear to reflect phylogenetic influences; it is more likely a functional characteristic that varies throughout postnatal life. Therefore, this chemosensory system has a high degree of plasticity relating to age and function, which in some instances can confound the use of characteristics as phylogenetic traits. Further study is needed to quantify VNO receptors in various species to determine if functional differences exist and if some species have more precocious VNO function than others.

Dental Maturation, Eruption, and Gingival Emergence in the Upper Jaw of Newborn Primates

“…All were obtained following perinatal mortality in captive settings (Appendix) with IACUC approval at Slippery Rock University. Because they were previously used to study midfacial development (e.g., Smith et al, 2001Smith et al, , 2003Smith et al, , 2005Smith et al, , 2011Smith et al, , 2014Shimp et al, 2003;Rossie and Smith, 2007;Carmody et al, 2008), each of the histological series included the maxillary and premaxillary dentition. When possible, recorded age was obtained from the source institutions (Appendix; and see Zehr et al, 2014).…”

Evolution of the nose and nasal skeleton in primates

“…67,68 Second, among hap-lorhines only tarsiers and New World monkeys possess vomeronasal organs with a neuroepithelium. 63,69,70 Third, the vomeronasal organ is absent or vestigial in all Old World monkeys, apes, and humans. [64][65][66]71,72 In New World monkeys, where receptor neurons for vomeronasal chemoreception Figure 5.…”

Ontogeny of the nasopalatine duct in primates

“…Clearly, the timing of NPD patency differs among callitrichids, and further examinations of more taxa will reveal how much variation exists. At present, it is interesting to note that the species with later patency of the NPD (S. geoffroyi), appeared to have less sensory epithelium in the VNO at birth (Smith et al, 2002(Smith et al, , 2003unpublished data).…”