ABSTRACT
The acuity and sensitivity of canine olfaction is widely recognized. To understand the basic principles underlying olfaction, it is crucial to identify the specific morphological, molecular, and physiological features of olfactory sensory neurons (OSNs; see Box 2.1 for abbreviations) and their neural connections along the olfactory pathway. One of the most intriguing aspects about the olfactory system is that the wiring of its neurons is not established early in development once and for all but is subject to lifelong turnover (Graziadei and Monti Graziadei 1985; Astic and Saucier 2001; Brann and Firestein 2014). This is in contrast to other regions of the nervous system and implies that during normal function, olfactory neurons are regularly lost by cell death and replaced by newly produced neurons (neurogenesis). Thus, understanding olfaction is not only a matter of molecular biology and physiology of an established neural network but includes also the analysis of processes that ensure adequate numbers and proper integration of adult-born neurons (Box 2.1).
