ISSN:
0741-0581
Keywords:
BEI
;
Calcium
;
Enamel
;
Radioautography
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Natural Sciences in General
Notes:
Backscattered electron imaging (BEI) can be used to obtain compositional contrast in biological structures because it detects differences in concentration of elements with different atomic number. Rat incisor enamel shows a banded pattern in the maturation zone when radioautography is used to reveal the location of injected 45Ca at the enamel surface. The bands of developed silver grains in the photographic emulsion that coats the enamel surface are ideal for atomic number contrast. The purpose of this study was to use BEI to analyze the radioautographic pattern with SEM resolution. One-month-old rats were injected with 45Ca and sacrificed at early (1 min, 5 min, 30 min), intermediate (4 h, 8 h), and late (1 day, 4 days) time intervals after injection. Whole incisors were dissected, the enamel organs were removed, and the enamel surface was coated with photographic emulsion and processed for radioautography. These radioautographed teeth were examined with a JEOL JSM-840 SEM equipped with a JEOL backscatter annular-type detector. At the early time intervals, light microscopic examination showed five or six broad black bands running obliquely across the teeth. These were separated by narrow white bands of unlabeled enamel. BEI resolved the presence of a delicate subbanding pattern within each dark band. At the intermediate time intervals, although the incisal bands persisted, only a diffusely blackened apical area was seen by light microscopy. BEI resolved bands in this apical region, but these showed no subbanding pattern. At the late time intervals, both light microscopy and BEI showed no banding, and the enamel was uniformly labeled. The significantly improved resolution obtained with BEI on surface radioautographs has revealed a previously undetected substructure in the 45Ca-labeled banding pattern seen in enamel maturation.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jemt.1060050406
Permalink
