Freeze-dried rat incisors were examined by high-resolution scanning electron microscopy (SEM) combined with energy-dispersive x-ray microanalysis (EDX) for determination of the correlation between the morphology of the enamel organ and the concentrations in the adjacent developing enamel matrix of calcium (Ca), phosphorus (P), and sulfur (S), as well as the CalP ratio. In SEM examination of the freeze-dried enamel organ, it was possible to identify the stages of enamel secretion, transition, and maturation, and furthermore to identify ruffle-ended and smooth-ended maturation ameloblasts. EDX analysis of the outer layer of forming and maturing enamel was carried out from the apical to the incisal end at interval points of approximately 50 μm. Ca and P concentrations increased gradually and continuously from the secretion zone to the end of the maturation zone, but never showed a steep rise in any of the zones examined. Maturing enamel overlaid by either ruffle-ended or smooth-ended maturation ameloblasts showed similar Ca and P concentrations. Throughout the outer enamel layer, the CalP molar ratio was fairly constant. Sulfur concentration began to decrease in the zone of enamel secretion, and was no longer detected in the middle of the maturation zone.
References
1.
Blumen, G. and Merzel, J. (1976): Autoradiographic Study with 35S-sodium Sulphate of Loss of Sulphated Glycosaminoglycans during Amelogenesis in the Guinea Pig, Arch Oral Biol21 :513-521.
2.
Boyde, A. and Reith, E.J. (1977): Qualitative Electron Probe Analysis of Secretory Ameloblasts and Odontoblasts in the Rat Incisor, Histochemistry50:347-354.
3.
Boyde, A. and Reith, E.J. (1978): Electron Probe Analysis of Maturation Ameloblasts of the Rat Incisor and Calf Molar, Histochemistry55:41-48.
4.
Boyde, A. and Reith, E.J. (1981): Display of Maturation Cycles in Rat Incisor Enamel with Tetracycline Labelling, Histochemistry72:551-561.
5.
Deakins, M. (1942): Changes in the Ash, Water and Organic Contents of Pig Enamel During Calcification, J Dent Res21 :429-435.
6.
Debari, K.; Takiguchi, R.; Higashi, S.; Sasaki, T.; and Garant, P.R. (1986): Correlated Observation and Analysis of Maturation Ameloblast Morphology and Enamel Mineralization, J Dent Res65:669-672.
7.
Deutsch, D. and Gedalia, I. (1980): Chemically Distinct Stages in Developing Human Fetal Enamel, Arch Oral Biol25:635-639.
8.
Deutsch, D. and Pe'er, E. (1982): Development of Enamel in Human Fetal Teeth, J Dent Res61(Sp Iss):1543-1551.
9.
Deutsch, D.; Shapira, L.; Alayoff, A.; Leviel, D.; Yoeli, Z.; and Arad, A. (1984): Protein and Mineral Changes During Prenatal and Postnatal Development and Mineralization of Human Deciduous Enamel. In: Tooth Enamel IV, R.W. Fearnhead and S. Suga, Eds., Amsterdam: Elsevier Science Publishers B.V., pp. 234-239.
10.
Embery, G. (1974): The Isolation of Chondroitin 4-(35S) Sulphate from the Molar Teeth of Young Rats Receiving Sodium (35S) Sulphate, Calcif Tissue Res14:59-65.
11.
Frank, R.M. (1970): Autoradiographie Quantitative de l'Amelogenese en Microscopie Electronique à l'âide de la Proline Tritiée Chez le Chat, Arch Oral Biol15:569-581.
12.
Garant, P.R. (1972): The Demonstration of Complex Gap Junctions Between the Cells of the Enamel Organ with Lanthanum Nitrate, J Ultrastruct Res40:333-348.
13.
Garant, P.R. and Sasaki, T. (1986): Ultracytochemistry of Ouabain-Sensitive K-Dependent p-Nitrophenyl Phosphatase in Rat Incisor Enamel Organ, Anat Rec216:1-9.
14.
Glick, P.L. (1979): Patterns of Enamel Maturation, J Dent Res58(B):883-892.
15.
Hammarstrom, L. (1971): Distribution in Developing Rat Enamel of Simultaneously Injected Fluoride and Calcium, Scand J Dent Res79:369-376.
16.
Hiller, C.R.; Robinson, C.; and Weatherell, J.A. (1975): Variations in the Composition of Developing Rat Incisor Enamel, Calcif Tissue Res18:1-12.
17.
Josephsen, K. (1984): Lanthanum Tracer Study on Permeability of Ameloblast Junctional Complexes in Maturation Zone of Rat Incisor Enamel Organ. In: Tooth Enamel IV, R.W. Fearnhead and S. Suga, Eds., Amsterdam: Elsevier Science Publishers B.V., pp. 251-255.
18.
Josephsen, K. and Fejerskov, O. (1977): Ameloblast Modulation in the Maturation Zone of the Rat Incisor Enamel Organ. A Light and Electron Microscopic Study, J Anat124:45-70.
19.
Kallenbach, E. (1967): Cell Architecture in the Papillary Layer of Rat Incisor Enamel Organ at the Stage of Enamel Maturation, Anat Rec157:683-698.
20.
Kallenbach, E. (1968): Fine Structure of Rat Incisor Ameloblasts During Enamel Maturation, J Ultrastruct Res22: 90-119.
21.
Kallenbach, E. (1980): Access of Horseradish Peroxidase (HRP) to the Extracellular Spaces of the Maturation Zone of the Rat Incisor Enamel Organ , Tissue Cell12:165-174.
22.
Leblond, C.P. and Warshawsky, H. (1979): Dynamics of Enamel Formation in the Rat Incisor Tooth, J Dent Res58(B): 950-975.
23.
Marsland, E.A. (1952): A Histological Investigation of Amelogenesis in Rats. Part II - Maturation, Br Dent J92: 109-119.
24.
McKee, M.D.; Martineau-Doize, B.; and Warshawsky, H. (1986): Penetration of Various Molecular-Weight Proteins into the Enamel Organ and Enamel of the Rat Incisor, Arch Oral Biol31:287-296.
25.
Nanci, A.; Bendayan, M.; and Slavkin, H.C. (1985): Enamel Protein Biosynthesis and Secretion in Mouse Incisor Secretory Ameloblasts as Revealed by High-Resolution Immunocytochemistry , J Histochem Cytochem33: 153-1160.
26.
Reith, E.J. (1970): The Stages of Amelogenesis as Observed in Molar Teeth of Young Rats, J Ultrastruct Res30:111-151.
27.
Reith, E.J. and Boyde, A. (1981a): Autoradiographic Evidence of Cyclical Entry of Calcium into Maturing Enamel of the Rat Incisor Tooth, Arch Oral Biol26:983-987.
28.
Reith, E.J. and Boyde, A. (1981b): The Arrangement of Ameloblasts on the Surface of Maturing Enamel of the Rat Incisor Tooth, J Anat133:381-388.
29.
Reith, E.J. and Cotty, V.F. (1967): The Absorptive Activity of Ameloblasts During the Maturation of Enamel, Anat Rec157 :577-588.
30.
Reith, E.J.; Schmid, M.I.; and Boyde, A. (1984): Rapid Uptake of Calcium in Maturing Enamel of the Rat Incisor, Histochemistry80:409-410.
31.
Robinson, C.; Briggs, H.D.; and Atkinson, P.J. (1981): Histology of Enamel Organ and Chemical Composition of Adjacent Enamel in Rat Incisors, Calcif Tissue Int33:513-520.
32.
Robinson, C.; Briggs, H.D.; Atkinson, P.J.; and Weatherell, J.A. (1979): Matrix and Mineral Changes in Developing Enamel, J Dent Res58(B): 871-880.
33.
Robinson, C.; Fuchs, P.; Deutsch, D.; and Weatherell, J.A. (1978): Four Chemically Distinct Stages in Developing Enamel from Bovine Incisor Teeth, Caries Res12:1-11.
34.
Robinson, C.; Hiller, C.R.; and Weatherell, J.A. (1974): Uptake of 32P-Labelled Phosphate into Developing Rat Incisor Enamel, Calcif Tissue Res15:143-152.
35.
Sasaki, T. and Garant, P.R. (1986a): An Ultrastructural Study of the Papillary Layer and its Vascular Bed in the Kitten Enamel Organ, Anat Rec214:353-364.
36.
Sasaki, T. and Garant, P.R. (1986b): Ultracytochemical Demonstration of ATP-dependent Calcium Pump in Ameloblasts of Rat Incisor Enamel Organ, Calcif Tissue Int39:86-96.
37.
Sasaki, T. and Garant, P.R. (1986c): A Study of Post-secretory Maturation Ameloblasts in the Cat by Transmission and Freeze-fracture Electron Microscopy, Arch Oral Biol31 :587-596.
38.
Sasaki, T.; Higashi, S.; Tachikawa, T.; and Yoshiki, S. (1984a): Absorptive and Digestive Functions of Maturation Ameloblasts in Rat Incisors. In: Tooth Enamel IV, R.W. Fearnhead and S. Suga, Eds., Amsterdam: Elsevier Science Publishers B.V., pp. 266-270.
39.
Sasaki, T.; Debari, K.; and Higashi, S. (1984b): Energy-dispersive X-ray Microanalysis and Scanning Electron Microscopy of Developing and Mature Cat Enamel, Arch Oral Biol29 :431-436.
Suga, S. (1982): Progressive Mineralization Pattern of Developing Enamel During the Maturation Stage, J Dent Res61:1532-1542.
42.
Takano, Y.; Crenshaw, M.A.; and Reith, E.J. (1982a): Correlation of 45Ca Incorporation with Maturation Ameloblast Morphology in the Rat Incisor, Calcif Tissue Int34:211-213.
43.
Takano, Y.; Crenshaw, M.A.; Bawden, J.W.; Hammarstrom, L.; and Lindskog, S. (1982b): The Visualization of the Patterns of Ameloblast Modulation by the Glyoxal Bis (2-hydroxyanil) Staining Method, J Dent Res61:1580-1586.
44.
Weinmann, J.P.; Wessinger, G.D.; and Reed, G. (1942): Correlation of Chemical and Histological Investigations on Developing Enamel, J Dent Res21:171-182.
45.
Weinstock, A. and Leblond, C.P. (1971): Elaboration of the Matrix Glycoprotein of Enamel by the Secretory Ameloblasts of Rat Incisor as Revealed by Radioautography After Galactose-H3 Injection, J Cell Biol51:26-51.
