PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 1820816

[The outermost enamel layer. A comparative scanning electron microscopic study].

J Rodde
View original source ↗Export metadata ↓

Abstract

The surface of the enamel layer was scanned in teeth of some representative animal species. We studied the structural organization of enamel at the surface of the teeth and also in subsurface. The surface layer was often described as "aprismatic". But, nevertheless, in mammals, prisms often reach the surface. They are packed together almost perpendicular to the periphery. The term "aprismatic" seems inappropriate. But the surface layer is particular in both a structural, physical and chemical standpoint. Its distribution on the enamel surfaces explains the variability of the etching patterns from an area to another on the same tooth.

Explore related subjects

Alligators and CrocodilesAnimalsDental EnamelFishesFossilsHumansMammalsMicroscopy, Electron, ScanningSpecies SpecificitySurface PropertiesComparative StudyEnglish AbstractJournal Article

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

J Rodde. 1991. [The outermost enamel layer. A comparative scanning electron microscopic study].. https://pubmed.ncbi.nlm.nih.gov/1820816/

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed1995

The evolution of WT1 sequence and expression pattern in the vertebrates.

WT1 is a Wilms' tumour predisposition gene, encoding a protein with four C-terminal Kruppel-type zinc fingers, which is also a major regulator of kidney and gonadal development. To pinpoint key regulatory domains involved in development and evolution of the vertebrate genitourinary system, we have isolated WT1 orthologues from all gnathostome classes. Partial nucleotide sequence from chick, alligator, Xenopus laevis and zebrafish reveals extensive conservation. Both the zinc fingers and the transregulatory domain exhibit a high level of similarity in all the species examined. However, of the two alternatively spliced regions only one, the three amino acid KTS insertion between zinc fingers 3 and 4, is found in species other than mammals. The 17 amino acid insertion at the C-terminal end of the transregulatory domain is present only in mammals. Residues with reported human pathological mutations are also unaltered across species, underlining their structural significance. Studies in chick and alligator reveal that the mammalian intermediate mesoderm expression pattern is conserved in birds and reptiles. A wider role in mesodermal differentiation is suggested by expression in some paraxial and lateral mesoderm derivatives.

Alligators and Crocodiles↗
PubMed1995

Responses to chronic hypoxia in embryonic alligators.

To investigate developmental responses to chronic hypoxia, we incubated alligator eggs at 17% O2 and 21% O2 for the entire course of embryonic development and for 5 months post-hatching. Hypoxic-incubated alligators hatched later and at a smaller size. Hematocrit was significantly higher in hypoxic-incubated animals immediately post-hatch. Allosteric modification of hemoglobin oxygen affinity did not appear to play a role in the adaptation to hypoxia, given equal nucleotide triphosphate-to-hemoglobin ratios in the hypoxic and normoxic groups. When acutely exposed to 21% O2, hypoxic-incubated alligators maintained oxygen consumption relative to their normoxic siblings despite their lower mass.

Alligators and Crocodiles↗