1.2.1 The Structure of the Primary Sensory Organ, Tongue:
Taste is primarily mediated by the endogenous gustatory organ, taste buds found within three of four types of papillae: fungiform, foliate, and circumvallate. The main muscular structure of the tongue is enclosed by an epithelial cell layer which contains small projections called papillae. Some regions of the papillae are specifically devoted to the detection of taste molecules and are called taste papillae or taste epithelium. The rest of the epithelium is non-gustatory epithelium covered with the fourth type of papillae, called filiform papillae. Filiform papillae are most numerous in number but do not contain any taste buds. They are pyramidal in shape and contain a narrow tail of …show more content…
Fungiform papillae are generally not continuous, and are interspaced by filiform papillae. A fungiform papilla generally only contains few taste buds. Foliate papillae at the lateral posterior portion of the tongue consist of parallel rows of folia and valleys and can contain hundreds of taste buds. At the posterior region of the tongue are the circumvallate papillae which extends in a V-shaped line across the root of the tongue in humans. Circumvallate papillae can contain thousands of taste buds. However, number of taste buds in each papilla varies across different species (Breslin and Huang, 2006; Jung et al., 2004; Kim et al., 2003; Roper, …show more content…
Again the number of taste cells in a taste bud varies across species. The elongated taste sensory cells are mature differentiated cells and are surrounded by a layer of keratinocytes and basal cells (Kinnamon, 1987; Stone et al., 2002; Finger, 2005). The basal cells that differentiate into TSCs are also known as Type IV taste cells. The apical tip of a TSC contains microvilli that extends into the taste pore and continuously samples the environment. Thus taste cells continuously experience wide fluctuations of tonicity, osmolarity and may come in contact with potential toxic compounds. Therefore, similar to olfactory system, TSCs area population of continuously renewing cells with an average life span of 8-12 days (Beidler and Smallman, 1965; Delay et al., 1986; Farbman, 1980 Okubo et al., 2009; Stone et al., 1995). The basal cells in the taste buds are also called progenitor cells that are believed to produce transit amplifying cells through asymmetrical division (Farbman et al., 1980). Subsequently these transit amplifying cells gives rise to the specialized TSCs (Beidler and Smallman, 1965; farbman, 1980; Delay et al., 1986; Miura et al.,
Taste is primarily mediated by the endogenous gustatory organ, taste buds found within three of four types of papillae: fungiform, foliate, and circumvallate. The main muscular structure of the tongue is enclosed by an epithelial cell layer which contains small projections called papillae. Some regions of the papillae are specifically devoted to the detection of taste molecules and are called taste papillae or taste epithelium. The rest of the epithelium is non-gustatory epithelium covered with the fourth type of papillae, called filiform papillae. Filiform papillae are most numerous in number but do not contain any taste buds. They are pyramidal in shape and contain a narrow tail of …show more content…
Fungiform papillae are generally not continuous, and are interspaced by filiform papillae. A fungiform papilla generally only contains few taste buds. Foliate papillae at the lateral posterior portion of the tongue consist of parallel rows of folia and valleys and can contain hundreds of taste buds. At the posterior region of the tongue are the circumvallate papillae which extends in a V-shaped line across the root of the tongue in humans. Circumvallate papillae can contain thousands of taste buds. However, number of taste buds in each papilla varies across different species (Breslin and Huang, 2006; Jung et al., 2004; Kim et al., 2003; Roper, …show more content…
Again the number of taste cells in a taste bud varies across species. The elongated taste sensory cells are mature differentiated cells and are surrounded by a layer of keratinocytes and basal cells (Kinnamon, 1987; Stone et al., 2002; Finger, 2005). The basal cells that differentiate into TSCs are also known as Type IV taste cells. The apical tip of a TSC contains microvilli that extends into the taste pore and continuously samples the environment. Thus taste cells continuously experience wide fluctuations of tonicity, osmolarity and may come in contact with potential toxic compounds. Therefore, similar to olfactory system, TSCs area population of continuously renewing cells with an average life span of 8-12 days (Beidler and Smallman, 1965; Delay et al., 1986; Farbman, 1980 Okubo et al., 2009; Stone et al., 1995). The basal cells in the taste buds are also called progenitor cells that are believed to produce transit amplifying cells through asymmetrical division (Farbman et al., 1980). Subsequently these transit amplifying cells gives rise to the specialized TSCs (Beidler and Smallman, 1965; farbman, 1980; Delay et al., 1986; Miura et al.,