Vomeronasal chemoreception in vertebrates: a study of the by Charles Evans

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Functional Morphology 29 monkeys (Platyrrhines), whereas centrally oriented nostrils separated by a narrow division are found in the African/Asiatic monkeys (Catarrhines). At present (Chap. 1), only the former group (Fig. 4) is known to be fully diosmic as adults (Evans and Grigorieva, 1995; Maier, 1997). On direct contact with scent-bearing material, the various rhinarial crevices possibly have some role in retaining samples until they are removed by the tongue. The median rhinarial fissure or sulcus provides for immediate access and oral transfer of fluids (Schilling, 1970; Prescott, 1977).

Chemoinvestigation and stimulus uptake is almost wholly dependent upon the tongue to bring particulates to the AOS entrance [Fig. 1(a)]. The divided tip is usually combined with a narrow tongue, but in burrowing species is combined with a broad fleshy base which also has a demarcated forked tip. The latter ranges from a slight notch, as in skinks, to the narrower and more deeply forked condition of many lizards, as in snakes [Fig. ). The MB is a unique structure typical of Ophidians, and forms a non-sensory intrusion whose prominence determines the volume of the VN lumen [Figs.

Whether stimulus access to the receptor surface is so improved has yet to be tested. 5 mm in snakes, and is distributed along the curved dorso-medial region. Its complexity is considerable (Fig. 15) with multicellular columns within which VNRs and supporting cells are elaborately intertwined (Halpern, 1992; Takami and Hirosawa, 1987). In parallel with the MOS, the relative number of receptor cells varies with the degree of AOS elaboration (Gove, 1979). The differing proportions of receptor cell abundance in vomerolfactory versus main olfactory epithelia range from a high level (Colubrids, Teiids) to intermediate (Skinks) or low (Iguanas).