part of ventral disc dorsal microribbon microribbon dorsal ribbon pr Trilaminar structure extending perpendicularly into the cytoplasm along the length of ventral disc microtubules in Giardia species (trophozoite stage). Constituents of dorsal microribbons (also called dorsal ribbons or microribbons) include alpha-coiled-helix proteins approximately 29 to 38 kDa in size. These proteins line the edges of the microribbons but are not found in microtubules. Tubulins are not found in microribbons. Due to the asymmetric nature of the Giardia trophozoite, this term is defined spatially as the trophozoite is viewed from the dorsal side, with the two nuclei dorsal to the ventral disc, and the ventral disc toward the anterior. cellular_component dorsal microribbon 2014-04-03T11:20:06Z GO:0097594 ventral disk dorsal microribbon ventral disc cellular anatomical structure