Interpretive tracing of a TEM of the Polar Plug region of Trichuris muris (adapted from fig. 9 of Preston and Jenkins (1985) [89]) showing the estimated dimensions of the missing Outer Layer of Polar Plug and Pellicula Ovi, both scaled to match photomicrographs of wholemounts in their fig. 1. Curly brackets represent terms introduced by Meng et al. (1986) [70] to describe what was seen in SEMs T. trichiura, where the Outer Layer of Polar Plug had apparently not been lost but had shrunken away from the collar wall leaving it surrounded by a moat-like trough.