Ultrastructural and immunohistochemical study of the influence of fluoride excess on the development of rat incisor tooth buds

Objective The purpose of this study was to establish the location and distribution of epithelial pearls and tooth buds in cleft palate fetuses, relative to the time of palate fusion. Design The facial skeletal structures, dental laminae, tooth buds, and epithelial pearls were examined in seven spontaneously aborted human fetuses, of which five had unilateral or bilateral cleft lip and palate or cleft palate. The sectioned fetuses were reconstructed by 3D-computer technology. Results Epithelial pearls were found in four of the investigated cases, of which one was a control specimen. They were located at the margins of the palatal shelves. In the cleft lip and palate cases, the cleft was found in the premaxilla between the first and second incisor tooth. The premaxilla was found to be hypoplastic in both bilateral cleft lip and palate cases and was totally absent in the unilateral cleft lip and palate case. The maxilla was hypoplastic in one case with unilateral cleft lip and palate. In all other specimens, it was developed symmetrically. Conclusions The results indicate that cleft lip and palate development may occur after the fusion of the frontonasal prominence with the maxillary prominence and the palatal shelves, as well as a nonfusion of the palatal shelves in the secondary palate.

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Immunoelectron microscopy of endothelial cells in rat incisor suggests that most basement membrane components are produced by young cells, whereas heparan sulfate proteoglycan is produced by both young and old cells.

Journal of Histochemistry & Cytochemistry ◽

10.1177/36.7.2968396 ◽

1988 ◽

Vol 36 (7) ◽

pp. 763-773 ◽

Cited By ~ 9

Author(s):

I C Murray ◽

C P Leblond

Keyword(s):

Endothelial Cells ◽

Basement Membrane ◽

Heparan Sulfate ◽

Collagen Iv ◽

Heparan Sulfate Proteoglycan ◽

Sulfate Proteoglycan ◽

Incisor Tooth ◽

Rat Incisor ◽

Membrane Components ◽

Basement Membrane Components

When periodontal capillaries of rat incisor tooth were immunostained for four basement membrane components (laminin, collagen IV, fibronectin, heparan sulfate proteoglycan), all four were detected in the secretory organelles of endothelial cells located within 3 mm of the tooth's proximal end, but only the proteoglycan was observed in cells located 4 mm away and beyond (Experiment I). [3H]-Thymidine autoradiography revealed that the endothelial cells located at the tooth's proximal end were young and actively dividing, whereas those located 4 mm or more away were older and generally quiescent (Experiment II). Since immunostaining of a cell's secretory organelles for a given substance indicates production of this substance, the first experiment shows that endothelial cells at the proximal end produce the four basement membrane components. The second experiment discloses that these cells are young. As for the endothelial cells located 4 mm or more beyond the proximal end, the first experiment reveals that they produce only heparan sulfate proteoglycan, while the second shows that they are relatively old. Production of laminin, collagen IV, and fibronectin only by young cells implies that these substances are long-lived and stable components of basement membrane, whereas production of the proteoglycan by both young and old cells implies that it is labile and continually replaced.

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Influence of fluoride on secretory pathway of the secretory ameloblast in rat incisor tooth germs exposed to sodium fluoride

Archives of Toxicology ◽

10.1007/s002040050294 ◽

1996 ◽

Vol 70 (7) ◽

pp. 420-429 ◽

Cited By ~ 18

Author(s):

S. Matsuo ◽

Tetsuichiro Inai ◽

Kojiro Kurisu ◽

Ken-ichi Kiyomiya ◽

Masaru Kurebe

Keyword(s):

Sodium Fluoride ◽

Secretory Pathway ◽

Incisor Tooth ◽

Rat Incisor ◽

Secretory Ameloblast ◽

Tooth Germs

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Subdivision of the Presecretory Region of the Rat Incisor Tooth

Journal of Dental Research ◽

10.1177/00220345790580025201 ◽

1979 ◽

Vol 58 (2_suppl) ◽

pp. 984-985 ◽

Cited By ~ 1

Author(s):

M.F. Al-Muddarris ◽

W.J. Dougherty

Keyword(s):

Incisor Tooth ◽

Rat Incisor

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Immunohistochemical evidence for the intracellular formation of basement membrane collagen (type IV) in developing tissues.

Journal of Histochemistry & Cytochemistry ◽

10.1177/28.12.6164715 ◽

1980 ◽

Vol 28 (12) ◽

pp. 1267-1274 ◽

Cited By ~ 32

Author(s):

G W Laurie ◽

C P Leblond ◽

I Cournil ◽

G R Martin

Keyword(s):

Basement Membrane ◽

Type Iv Collagen ◽

Early Stage ◽

Basement Membranes ◽

Incisor Tooth ◽

Rat Incisor ◽

Type Iv ◽

Stage Of Development ◽

Basement Membrane Collagen ◽

Membrane Collagen

Antibodies to type IV collagen obtained from the basement membrane of the mouse EHS tumor were incubated with sections of rat incisor teeth and other tissues for immunostaining by direct or indirect methods. In all locations, the immunostaining was pronounced in basement membranes in which it was restricted to the "basal lamina" layer, from which "bridges" often extended to nearby basal laminae. Usually no immunostaining was detectable in the cells associated with the basement membranes. However, examination of the capillaries at the posterior extremity of the rat incisor tooth, where tissues are at an early stage of development, showed immunostaining not only of the basement membrane, but also of the endothelial cells. The staining was localized in rough endoplasmic reticulum cisternae, some Golgi saccules and their peripheral distensions, and structures believed to be secretory granules. These findings suggest that the synthesis of type IV collagen proceeds along the classical secretory pathways through rough endoplasmic reticulum and Golgi apparatus. At the same time, immunostaining was usually lacking in the cells of the capillaries that had migrated about 2 mm away from the posterior end of the incisor tooth and also in the cells of most other tissues examined, even though the associated basal laminae were reactive. It is, therefore, presumed that the production of type IV collagen may be high in cells at an early stage of development and that any later production and turnover of basement membrane collagen can only be minimal.

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Dynamics of Enamel Formation in the Rat Incisor Tooth

Journal of Dental Research ◽

10.1177/00220345790580024901 ◽

1979 ◽

Vol 58 (2_suppl) ◽

pp. 950-979 ◽

Cited By ~ 104

Author(s):

C.P. Leblond ◽

H. Warshawsky

Keyword(s):

Amino Acids ◽

Cell Membrane ◽

Organic Material ◽

Organic Matrix ◽

Incisor Tooth ◽

Enamel Formation ◽

Rat Incisor ◽

Full Size ◽

Matrix Deposition ◽

Mineral Deposition

Enamel formation was reviewed by morphology and radioautography in rat incisors. Labeled amino acids and sugars were used as matrix precursors whereas labeled calcium monitored mineral deposition. All ameloblasts synthesize organic material, but only cells in the zone of secretion release labeled matrix. The pattern of matrix deposition indicates that enamel rods are elaborated by Tomes' processes within cavities formed by interrod partitions. The latter are elaborated by cytoplasmic projections from adjacent ameloblasts. Initially - labeled matrix is added as a band near the cells. With time the label randomizes throughout the entire immature enamel and most of it is lost in the zone of maturation. However, a glycoprotein component attributed to remnants of Tomes' process membrane persists in mature enamel. Labeled calcium is incorporated into crystals which grow at a uniform rate throughout the entire layer of enamel in the zone of secretion and up to the middle of the zone of maturation. The ribbon-like crystals are built close to the cell membrane and elongate as the cell recedes. Crystal elongation occurs in the same location as new matrix is deposited; that is, rod crystals are related to Tomes' processes and interrod crystals, to cytoplasmic projections. The crystals grow to full size mainly by thickening and this growth presumably displaces the organic matrix.

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