ISSN:
1432-0878
Keywords:
Intestinal mucus
;
Biocrystallization
;
X-ray microanalysis
;
Electron diffraction
;
X-ray diffraction
;
Eel (Anguilla anguilla)
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary In the posterior intestine of the sea-water eel, mucus plays an important role in biocrystallization of calcium ions. By means of transmission and scanning electron microscopy associated with X-ray microanalysis and X-ray diffraction it has been possible to determine the role of mucous fibers as nucleation sites. Biocrystallization occurs in 2 steps: (1) Calcification of mucus. As soon as mucus is excreted in the intestinal lumen, it is loaded with calcium, as shown by lanthanum affinity and X-ray microanalysis on freeze-dried tissues. (2) Genesis of crystals. Needleshaped crystallites build up in coalescent spherites in the intestinal lumen near the microvilli. Genesis occurs as follows: (a) crystallite mineralization by nucleation in an organic matrix composed of glycoproteinaceous mucous fibers, followed by the appearance of spherites; (b) coalescence in spherites and association of spherites in rhombohedra; (c) extrusion of organic material during the final step of crystallization.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00218793
