ABSTRACT
Among vertebrate embryos, sensory structures develop according to an invariant orderly sequence (Bradley &Mistretta, 1975; Gottlieb, 1971). In that developmental succession, the morphogenesis of the chemosensory modalities (oral and nasal chemoreception) closely follows that of the early somesthesic and vestibular modalities, but precedes the auditory and visual modalities. Despite the fact that this precocity of chemosensory structures has been well established, the possibility of a prenatal onset of olfactory functions was never seriously considered. To support this presumed sensory hindrance, some influential scholars argued for either the necessity for chemicals to be airborne in order to trigger an olfactory sensation (Carmichael, 1970; Gueubelle, 1984; Preyer, 1881), the absence of fluid currents flowing through the nose (Humphrey, 1978), or the total lack of odorous compounds in the prenatal environment (Feldman, 1920; Ferril, 1987).
