part of overlaps start stage end stage opercle Dermal bone that articulates anteriorly with the hyomandibula. The opercle is paired and typically the largest bone of the opercular series. It is derived from the neural crest and is located in 2nd pharyngeal arch. zebrafish_anatomy opercles ZFA:0000250 TAO:0000250 opercular flap dermatocranium dorsal hyoid arch dermal bone operculohyoid ligament unknown adult