Digital Commons Network^™

Marsupial And Monotreme Enamel Structure, K. S. Lester, A. Boyde, C. Gilkeson, M. Archer

Scanning Microscopy

We present some recent developments in our understanding of two basic questions: the origin, extent, nature and course of marsupial enamel tubules; and the characterisation of monotreme enamel, more particularly, the prismatic nature of platypus enamel.

Methods used included SEM of methacrylate casts of marsupial enamel tubules, worn and cut surfaces of whole marsupial teeth, developing and erupted platypus teeth, and a well-developed molar of the newly discovered Miocene ornithorhynchid Obdurodon sp., and tandem scanning reflected light microscopy of intact marsupial teeth.

We conclude that there are significant species differences with respect to prism shape, row formation and tubule disposition …

Otoconia As Test Masses In Biological Accelerometers: What Can We Learn About Their Formation From Evolutionary Studies And From Work In Microgravity?, Muriel D. Ross, Kathleen M. Donovan

Scanning Electron Microscopy

This paper reviews previous findings and introduces new material about otolith end organs that help us to understand their functioning and development. In particular, we consider the end organs as biological accelerometers. The otoconia are dealt with as test masses whose substructure and evolutionary trend toward calcite may prove significant in understanding formation requirements. Space-flight helps illuminate the influence of gravity, while right-left asymmetry is suggested by study of certain rat strains.