Meeting Abstract
Cypriniform fishes possess a median sesamoid bone in their upper jaw, termed the kinethmoid; it is a synapomorphy for the order and facilitates premaxillary protrusion. The kinethmoid is attached via ligaments to bones in and around the upper jaw: the maxillae, premaxillae, palatines and neurocranium. The jaw muscles, specifically the A1 division of the adductor mandibulae, insert on the maxillae and initiate forces that are transmitted to these kinethmoid ligaments. This rotates the kinethmoid, pushing the premaxillae into a protruded state. Little has been done to identify the composition or function of these kinethmoid-associated ligaments. Furthermore, teleosts possess a wide range of cartilage-like connective tissues (CLCTs), but little is known about their function and most work has been qualitative. Using histology, the morphology of each kinethmoid ligament was studied and various stains were applied to determine the components of the extracellular matrix. ImageJ was used to determine the ratios of cells to extracellular matrix (ECM) as well as absolute cell size in an effort to begin to standardize the identification methods in various teleost CLCTs. The premaxillary ligament, which undergoes compressive forces during feeding, is composed of hyaline cell cartilage (HCC). HCC is a highly cellular tissue with little ECM, permitting the kinethmoid to push the premaxillae into a protruded state. Gaining knowledge of the composition and function of the CLCTs in teleosts can give us not only a better understanding of fish feeding and premaxillary protrusion, but this information can be applied to other anatomical and morphological structures in teleosts, aiding in the a more complete understanding of teleost anatomy.
