Figure 12 in Proboscis sensory cells in Nemertea: comparative morphology and phylogenetic implications

Figure 12. Transmission electron micrographs of proboscis nonciliated sensory cells of hoplonemerteans. A, Ototyphlonemertes valentinae, panoramic view of the apical surface of the proboscis epithelium showing the receptor process (asterisk) of a nonciliated sensory cell. B, O. valentinae, high magnification of a longitudinal section showing the base of the receptor process of a nonciliated sensory cell. C, O. valentinae, transverse section of the receptor process of a nonciliated sensory cell showing the central shaft (asterisk) surrounded by a ring of microvilli (arrowheads). D, Tetrastemma stimpsoni, longitudinal section of a papilla of the proboscis epithelium. E, Te. stimpsoni, transverse section of a papilla of the proboscis epithelium. A high-magnification inset shows the receptor process of a nonciliated sensory cell: a central shaft (asterisk) surrounded by a ring of microvilli (arrowhead). F, Te. stimpsoni, transverse section of a papilla tip. G, Te. stimpsoni, higher magnification of a papilla tip in the region of apicolateral junctions (arrowheads). H, Te. stimpsoni, transverse section of the body (asterisk) of a nonciliated sensory cell. The distal region of the cell body contains the Golgi complex (gc) and mitochondria (m). I, Te. stimpsoni, high magnification of the perinuclear cytoplasm of a nonciliated sensory cell showing the filament bundles (arrowhead) extending from the receptor process. J, Te. stimpsoni, high magnification showing the basal process (asterisks) of a nonciliated sensory cell extending into a pore (p) in the extracellular matrix (ecm). Trunks (asterisks) of the basiepithelial nerve plexus are located under the pore (p).