Odor-detecting olfactory sensory neurons residing in the nasal olfactory epithelium (OE) are the only neurons in direct contact with the external environment. As a result, these neurons are subjected to chemical, physical, and infectious insults, which may be the underlying reason why neurogenesis occurs in the OE of adult mammals. This feature makes the OE a useful model for studying neurogenesis and neuronal differentiation, with the possibility for systemic as well as local administration of various compounds and infectious agents that may interfere with these cellular processes. Several different chemical compounds have been shown to cause toxic injury to the OE, which can be used for OE ablation. We, and others, have found that the systemic administration of the hyperthyroid drug,

The mammalian neocortex, the outer layer of the cerebrum and most recently evolved brain region, is characterized by its unique areal and laminar organization. Distinct cortical layers and areas can be identified by the protein expression of graded transcription factors and molecular determinants that define the identity of different projection neurons. Thus, specific detection and visualization of protein expression is crucial for assessing the identity of neocortical neurons and, more broadly, for understanding early and late developmental mechanisms and function of this complex system. Several immunostaining/immunofluorescence methods exist to detect protein expression. Published protocols vary with regard to subtle details, which may impact the final outcome of the immunofluorescence.