Anatomy and Ontogeny of the Mandibular Symphysis in Alligator mississippiensis.

Title

Anatomy and Ontogeny of the Mandibular Symphysis in Alligator mississippiensis.

Creator

Lessner Emily J; Gant Cortaiga A; Hieronymus Tobin L; Vickaryous Matthew K; Holliday Casey M

Publisher

Anatomical record (Hoboken, N.J. : 2007)

Date

2019
2019-03

Description

Crocodylians evolved some of the most characteristic skulls of the animal kingdom with specializations for semiaquatic and ambush lifestyles, resulting in a feeding apparatus capable of tolerating high biomechanical loads and bite forces and a head with a derived sense of trigeminal-nerve-mediated touch. The mandibular symphysis accommodates these specializations being both at the end of a biomechanical lever and an antenna for sensation. Little is known about the anatomy of the crocodylian mandibular symphysis, hampering our understanding of form, function, and evolution of the joint in extant and extinct lineages. We explore mandibular symphysis anatomy of an ontogenetic series of Alligator mississippiensis using imaging, histology, and whole mount methods. Complex sutural ligaments emanating about a midline-fused Meckel's cartilage bridge the symphysis. These tissues organize during days 37-42 of in ovo development. However, interdigitations do not manifest until after hatching. These soft tissues leave a hub and spoke-like bony morphology of the symphyseal plate, which never fuses. Interdigitation morphology varies within the symphysis suggesting differential loading about the joint. Neurovascular canals extend throughout the mandibles to alveoli, integument, and bone adjacent to the symphysis. These features suggest the Alligator mandibular symphysis offers compliance in an otherwise rigid skull. We hypothesize a fused Meckel's cartilage offers stiffness in hatchling mandibles prior to the development of organized sutural ligaments and mineralized bone while offering a scaffold for somatic growth. The porosity of the dentaries due to neurovascular tissues likely allows transmission of sensory and proprioceptive information from the surroundings and the loaded symphysis. Anat Rec, 2019. (c) 2019 Wiley Periodicals, Inc.

Subject

feeding apparatus; Meckel's cartilage; sutural ligament; trigeminal

Identifier

Rights

Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).

NEOMED College

NEOMED College of Medicine

NEOMED Department

Department of Anatomy & Neurobiology

Citation

Lessner Emily J; Gant Cortaiga A; Hieronymus Tobin L; Vickaryous Matthew K; Holliday Casey M, “Anatomy and Ontogeny of the Mandibular Symphysis in Alligator mississippiensis.,” NEOMED Bibliography Database, accessed June 25, 2021, https://neomed.omeka.net/items/show/6251.

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