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The Eastern oyster, Crassostrea virginica, produces a tough, fracture-resistant protective composite shell that is composed of calcite (a polymorph of calcium carbonate) as well as organic material (proteins, glycoproteins). Scientists have examined the shell formation process in molluscs for many decades and have proposed two models for the shell formation process. The matrix-mediated model focuses on the role of proteins as nucleation sites for calcite crystal formation while the hemocyte-mediated model proposes the role of oyster blood cells for transport of calcite nuclei to the shell formation front. Specifically, the hemocyte-mediated model proposes that the hemocytes of C. virginica contain calcium carbonate crystals that are transported through the tissues and deposited at the shell formation front. These nuclei then grow and coalesce to form the typical layered organic-mineral shell structure. This study focused on determining if hemocytes were capable of producing mineral structure when cultured outside the organism. Hemocytes were collected from notched oysters and cultured for up to ninety six hours ex vivo in order to determine if crystal formation occurred. Microscopic analysis (scanning electron microscopy, SEM) of the hemocyte samples revealed crystal structures within and around cells cultured on glass substrates. The process of shell formation is very complex and probably involves both the matrix-mediated and hemocyte-mediated model for movement of both organic and mineral resources to the shell formation front. While elucidation of the basic biological process of shell formation is of great interest, there is potential for use of hemocyte crystal deposition for development of biomedical implant coatings. The biocompatible oyster-derived material may function as a better interface for integration of tissue with metallic implants.
Karolyn M. Hansen
Primary Advisor's Department
Stander Symposium poster
Prall, Cristina R., "The Role of Hemocytes in Shell Formation in the Eastern Oyster, Crassostrea virginica" (2012). Stander Symposium Posters. 135.