trigone /trɪˈɡəʊn/ noun2 •A smooth triangular area on the inner surface of the bladder, bounded by the apertures of the ureters and urethra; a similar region of a mitral valve •One of the thickenings of the cell wall at the angles where several cells join.Leaf cells are about 25–30 μm, with thin walls and bulging trigones. — 1992 formstrigones
