Electron-microscopic and microprobe analyses on the pigmented and unpigmented enamel of Sorex (Insectivora)

Abstract

Sorex belongs to the Insectivora and has a pigmented tooth enamel due to iron. The pigmented enamel (PE) has a mean Ca/P weight ratio, analyzed by quantitative electronprobe X-ray microanalysis, of about 1.9 (mean molar Ca/P ratio 1.46), and the unpigmented enamel (UE) a Ca/P weight ratio of about 2.0 (mean molar Ca/P ratio 1.59). The PE has a higher iron content (with a value of about 8%) than the UE, as shown by microanalysis of ultrathin sections. Laser microprobe mass analysis (LAMMA) has shown that the carbonate content in the UE is higher than in the PE. In the LAMMA spectrum of the negatively charged ions the carbonate lines could be compared directly with those of negatively charged iron ions. The pigmentation is associated with a low Ca/P ratio but may transfer mechanical strength and acid resistance strength to the PE.

Tubule formation and elemental detection in developing opossum enamel

“…A similar effect on Ca/P may also occur if the opossum tooth germ contained the same carbonate species. While such a result is unknown, carbonate has been detected in the tubular enamel of the shrew (Kozawa et al, 1988) by laser microprobe mass analysis. It remains to analyze the opossum enamel for carbonate by this or other spectroscopic means.…”

“…In a study of mature kangaroo enamel, Palamara et al (1981) suggest that the enamel tubules are channels for dissolution and reprecipitation of materials associated with disturbed areas of crystal growth; using the technique of ion mill-ing to obtain thin areas of mineralized sections, they also detect the presence of octacalcium phosphate (OCP) in mature kangaroo enamel. Finally, in teeth of the shrew, Kozawa et al (1988) suggest the possibility that carbonate is transported from predentin to unpigmented enamel via the dentinal tubules by virtue of their continuity with the enamel tubules.…”

Elemental Analysis of Soricine Enamel: Pigmentation Variation and Distribution in Molars of Blarina Brevicauda

“…A. Akersten, in litt. ;Dötsch and Koeningswald 1978;Kozawa et al 1988aKozawa et al , 1988bLunt and Noble 1975;Miles 1963;Soderlund et al 1992). However, unlike in rodents, shrew tooth pigmentation is not limited to the incisors and is found throughout the toothrow.…”

“…However, unlike in rodents, shrew tooth pigmentation is not limited to the incisors and is found throughout the toothrow. Even though pigmentation in shrews is limited to the superficial aprismatic enamel layer (Dötsch and Koenigswald 1978;Koenigswald 1997), the pigmented layer in shrews is reported to be substantially thicker than in rodents (Kozawa et al 1988a(Kozawa et al , 1988b. Although pigmented enamel is generally considered to increase wear resistance of teeth, there are no experimental data to support this assumption.…”

“…Although researchers have analyzed the histological structure and development of pigmented enamel (Akersten et al 2001(Akersten et al , 2002Koenigswald 1997;Kozawa et al 1988aKozawa et al , 1988bW. A. Akersten, in litt.…”