nacreous layer

nacreous layer

the pearly, innermost layer of the shell of a mollusc secreted by the mantle epithelium.
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2003) isolated a protein complex composed of pearlin and pearl keratin from the nacreous layer of pearl beads and oyster shells, which could induce aragonite crystallization.
The elements in prismatic layer and nacreous layer of Haliotis discus hannai Ino shells were analysed using Energy dispersive spectrometer.
If we rear the oyster for a longer period, the lustre of the nacreous layer might be decreased, because the surface of the nacreous layer becomes more irregular," said Dr Hiromichi Nagasawa, a scientist at the University of Tokyo.
Internal growth annuli were defined as areas of discontinuity of the prismatic layer that extended from the nacreous layer to the periostracum (Fig.
But it is the aragonite form found in the inner, nacreous layer that makes the shell remarkably resistant to breakage.
Whole shell destruction does not allow for discrimination between shells that have a thicker proportion of a layer such as the prismatic layer to the periostracum or nacreous layer.
Once the outer prismatic layer has reached full thickness (80-90 [micro]m in Laternula rostrata), a nacreous layer is secreted below (Aller, 1974).
Thickness of the nacreous layer of all pearls was measured using a coherence tomographic scanner (OSLF-1500; Shenzhen Certainn Technology Co.
In Malleus regulus, the organic walls of the prisms vanish abruptly some distance in front of the boundary with the nacreous layer (where there is no appreciable intermediate organic pellicle) (Fig.
The prisms of the prismatic shell layer are composed of single-crystal fibers radiating from spheruliths, whereas in the nacreous layer the structure is similar to that of a brick wall, with tablets in each layer offset with respect to those in the layers above and below them.
Electron microscopy of crystal growth of the nacreous layer of the oyster Crassostrea virginica.