bourrelet (noun,ascus term, pl. bourrelets) – literally "saddle" (French); a structural part of the tholus, referring to the tholus flanks on either side of the ocular chamber, whether reacting in iodine or not. Sometimes the bourrelet forms ascus pendants that extend into the ascoplasm. In some asci the tholus flanks of the bourrelet merge at the tip above the ocular chamber, in other asci an axial plug is separated from the bourrelet by apical furrows. This is:part of ascus.