Meeting Abstract

P3.27  Saturday, Jan. 5  3D Modeling of the Lateral Somitic Frontier TULENKO, F.J.*; SHEARMAN, R.M.; SFERLAZZO, M.; WINSLOW, B.B.; BURKE, A.C.; Wesleyan University; Wesleyan University; Wesleyan University; Wesleyan University; Wesleyan University ftulenko06@jcu.edu

We use 3D modeling to visualize changes in the lateral somitic frontier (LSF) during chick and mouse development. The LSF marks the interface between two distinct embryonic domains. The primaxial domain contains somitic cells that differentiate in a somitic environment, whereas the abaxial domain contains somitic migratory cells that differentiate in a lateral plate (LP) environment. The initial boundary between somitic and LP mesoderm is uniform along the post-cranial anteroposterior (AP) axis of the embryo. As development proceeds, the topography of the frontier varies because of differential growth of primaxial and abaxial tissues along the AP axis. Interestingly, the frontier is interrupted by specific muscles, nerves, and skeletal elements. We visualize the LSF in transgenic mice with a LP-specific Cre recombinase driving alkaline phosphatase, and in avian embryos by transplanting quail presomitic mesoderm into chick hosts. We use 3D models generated with Amira^TM to track the dynamics of the frontier during morphogenesis at different anatomical resolutions (e.g., whole embryos, specific musculoskeletal elements, and spinal nerves) in both species. Specifically, we reconstructed primaxial and abaxial components of the mouse pectoral girdle, and are modeling this boundary in the avian shoulder. We are generating a developmental series of whole-body reconstructions of the LSF in mice, including spinal nerve patterning. Preliminary data suggest that major changes in the trajectory of spinal nerves are coincident with the frontier. Visualizing morphological data in 3D will help clarify patterns of cell differentiation in the context of the embryonic environment. We hypothesize that the LSF represents a boundary that separates two independent but coordinated global patterning domains in the developing embryo.