Green fluorescent protein (GFP) expression patterns in the olfactory epithelium of GFP transgenic cloned Jinhua pigs

Domestic pigs possess a well-developed sense of smell. However, the morphology of the porcine olfactory epithelium (OE) is poorly understood. Recently, several strains of transgenic cloned pigs that are presumed to ubiquitously express green fluorescent protein (GFP) have been created. Thus, the purpose of this study was to elucidate the features of porcine OE using the tissues of GFP transgenic cloned pigs. Based on observations of Hematoxylin and Eosin staining and measurements of thickness, porcine OE tissue portions were classified into three categories (thick, standard, and thin). Cryosections revealed that the prominent GFP signals were expressed in olfactory sensory neurons (OSN), Bowman's glands, and olfactory nerve. A few GFP-expressing sustentacular cells were seen; however, the intensity of GFP fluorescence was slight. In the thick portion, numerous GFP-expressing polygonal OSN that did not possess dendrites were found. In the standard portions, GFP-expressing cells had longitudinal dendrites. A few GFP-expressing cells were found in the thin portion. In the thick and standard portions, most of the prominent GFP-expressing cells were positive for olfactory marker protein. Moreover, double immunofluorescence staining with boiled GFP and Sox2 antibody revealed that GFP expression patterns in OSN are synchronized with Sox2 immunoreactive patterns.