The sense of smell, its signalling pathways, and the dichotomy of cilia and microvilli in olfactory sensory cells

Smell is often regarded as an ancillary perception in primates, who seem so dominated by their sense of vision. In this paper, we will portray some aspects of the significance of olfaction to human life and speculate on what evolutionary factors contribute to keeping it alive. We then outline the functional architecture of olfactory sensory neurons and their signal transduction pathways, which are the primary detectors that render olfactory perception possible. Throughout the phylogenetic tree, olfactory neurons, at their apical tip, are either decorated with cilia or with microvilli. The significance of this dichotomy is unknown. It is generally assumed that mammalian olfactory neurons are of the ciliary type only. The existance of so-called olfactory microvillar cells in mammals, however, is well documented, but their nature remains unclear and their function orphaned. This paper discusses the possibility, that in the main olfactory epithelium of mammals ciliated and microvillar sensory cells exist concurrently. We review evidence related to this hypothesis and ask, what function olfactory microvillar cells might have and what signalling mechanisms they use

Suckling Odours in Rats and Mice: Biological Substrates that Guide Newborns to the Nipple

Proceedings Paper 12th Meeting of the Chemical Signals in Vertebrates, Aug 28-31, 2011, Berlin, GERMANY ; http://www.springer.com/life+sciences/ecology/book/978-1-4614-5926-2International audienceIt is a general strategy for mammalian females to emit odour signals to direct their offspring to the mammae and to motivate their suckling. The survival of newborns depends on their own capacities to exploit the cues emitted by their mother, or by conspecific lactating females, and to direct their behaviour to the vital targets on the mother's body-the nipples. This chapter synthesises data on some natural substrates that contribute to nipple searching and grasping in the newborns of (laboratory strains of) two phylogenetically close species, Rattus norvegicus and Mus musculu