The structure of the eggshell and eggshell membranes of Crocodylus niloticus

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dc.contributor.author Lensink, Antonia Vergina
dc.contributor.author Swan, Gerry E.
dc.contributor.author Myburgh, Jan G.
dc.date.accessioned 2024-03-26T12:41:47Z
dc.date.available 2024-03-26T12:41:47Z
dc.date.issued 2023-04
dc.description.abstract The macro- and microstructure, elemental composition, and crystallographic characteristics of the eggshell and eggshell membranes of the Crocodylus niloticus eggwas investigated using optical and electron microscopy, energy-dispersive X-ray spectroscopy (EDS), electron backscatter diffraction (EBSD) and computerised tomography. The translucent ellipsoid egg is composed of two basic layers, the outer calcified layer referred to as the shell and an inner organic fibre layer, referred to as the shell membrane. The outer inorganic calcite shell is further divided into an external, palisade and mammillary layers with pore channels traversing the shell. The external layer is a thin layer of amorphous calcium and phosphorus, the underlying palisade layer consist of irregularwedge-shaped crystals composed calcite with traces of magnesium, sodium, sulphur and phosphorus. The crystals are mostly elongated, orientated perpendicular to the shell surface ending in cone-shaped knobs, which forms the inner mammillary layer. The elemental composition of the mammillae is like that of the palisade layer, but the crystal structure is much smaller and orientated randomly. The highest number of mammillae and shell pores are found at the equator of the egg, becoming fewer towards the egg poles. The shell thickness follows the same pattern, with the thickest area located at the equator. The eggshell membrane located right beneath and embedded in the mammillary layer of the shell; it is made up of unorganised fibre sheets roughly orientated at right angles to one another. Individual fibres consist of numerous smaller fibrils forming open channels that run longitudinally through the fibre. en_US
dc.description.department Anatomy and Physiology en_US
dc.description.librarian am2024 en_US
dc.description.sdg SDG-03:Good heatlh and well-being en_US
dc.description.sponsorship HWSETA and the IUCN-SSC Crocodile Specialist Group. en_US
dc.description.uri http://wileyonlinelibrary.com/journal/jmi en_US
dc.identifier.citation Lensink, A. V., Swan, G. E., & Myburg, J. G. (2023). The structure of the eggshell and eggshell membranes of Crocodylus niloticus. Journal of Microscopy, 290, 23–39. https://DOI.org/10.1111/jmi.13173. en_US
dc.identifier.issn 0022-2720 (print)
dc.identifier.issn 1365-2818 (online)
dc.identifier.other 10.1111/jmi.13173
dc.identifier.uri http://hdl.handle.net/2263/95359
dc.language.iso en en_US
dc.publisher Wiley en_US
dc.rights © 2023 The Authors. This is an open access article under the terms of the Creative Commons Attribution License. en_US
dc.subject Computed tomography en_US
dc.subject Crocodylus niloticus en_US
dc.subject Egg en_US
dc.subject Electron microscopy en_US
dc.subject Light microscopy en_US
dc.subject Energy-dispersive X-ray spectroscopy (EDS) en_US
dc.subject Electron backscatter diffraction (EBSD) en_US
dc.subject SDG-03: Good health and well-being en_US
dc.title The structure of the eggshell and eggshell membranes of Crocodylus niloticus en_US
dc.type Article en_US


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