Abstract
Neuronal apoptosis is important in the developmental sculpting of a normal nervous system and also in the loss of neurons caused by neurodegenerative disease, ischemia or trauma. In a developing embryo, exquisite mechanisms of regulation exist to balance factors that control neuronal birth and death within a given neuronal group, so that sufficient neurons develop and survive to elicit normal function. Postnatally, the only part of the mammalian nervous system where many of these regulatory balance mechanisms are retained is the olfactory epithelium (OE). During the last 30 years, researchers investigating olfactory receptor neuron cellular and developmental biology have focussed on the regeneration of the neuronal population within the olfactory neuroepithelium, following the induced death of the mature neuronal population. This body of work has thus far overshadowed the equally important and intrinsically linked phenomenon of the death of mature olfactory receptor neurons, which is required to initiate regeneration. The purpose of this review is to reveal what has been established about the different forms of cell death that can occur in neurons of the olfactory epithelium, and highlight the identified proβ and antiβapoptotic pathways that control the normal and induced turnover of olfactory receptor neurons. Microsc. Res. Tech. 58:204β215, 2002. Β© 2002 WileyβLiss, Inc.