The development of the hamster lower incisor as observed by electron microscopy

Watson, Michael; Avery, James K.

doi:10.1002/aja.1000950105

Cited by 117 publications

(26 citation statements)

References 28 publications

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“…and distal portions (Warshawsky, 1968). The infranuclear cytoplasm houses mast of the ceilla mitochondria (Watson and Avery, 1954), sdme rER, and the proxiIMI junctional complex and ceU web (Ronnholm, 1962). The supranuclear r.j cytoplasm contains much rER orientated paraI leI ta the long axis of the cell and an extensive tubular-shaped Golgi apparatus (Kallenbach et al, 1963).…”

Section: The Enamel Organ In the Secretion Zonementioning

confidence: 99%

In vivo experimentation on rat incisor enamel organs through a surgical window

McKee

Warshawsky

1984

Anat. Rec.

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Experimental agents administered systemically are costly and often toxic to animals. An in vivo technique has been developed whereby a surgical window in the alveolar bone allows selected areas of the rat incisor enamel organ and underlying enamel to be exposed to various drugs, radiolabeled molecules, and molecular weight markers. Sherman rats weighing 100 gm were anesthetized and the inferior surface of each hemimandible was surgically exposed. A slow‐speed dental hand drill was used to drill a small hole through the alveolar bone overlying the secretion or maturation zones of the enamel organ. The wound was closed and during recovery the mechanical trauma to the underlying tissue moved away from the hole due to the continuous eruption of the tooth. Two to 5 days later the hole was reexposed and microinjections of 3H‐proline, 125I‐salmon calcitonin, vinblastine sulphate, and normal saline (as control) were administered through the hole with a micro‐manipulator and a microliter syringe. Radioautographic detection of 3H‐proline incorporation in secretory ameloblasts and enamel at 10 minutes, 30 minutes, 1 hour, 4 hours, 1 day, and 2 days after microinjection was identical to that obtained previously by systemic injection. Two hours after microinjection of vinblastine sulphate the cellular response was again identical to that following systemic injection; 125I‐salmon calcitonin (M.W. ∼ 3,600D) was used as a molecular weight marker and was seen to diffuse into the enamel of the maturation zone at 10 minutes after microinjection. This study has demonstrated the feasibility of this new technique for experimentation on rat incisor enamel organs.

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Section: The Enamel Organ In the Secretion Zonementioning

confidence: 99%

In vivo experimentation on rat incisor enamel organs through a surgical window

McKee

Warshawsky

1984

Anat. Rec.

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“…According to Hench and Andersson (39) Seemingly, collagen fibres provide scaffolding with the sites required for the micro-nucleation of apatite crystals (42), taking place an interdigitation of the collagen with the surface of the material (5). Apatite crystals grow epitaxially across the bone-implant interface; this means, in bone biology terms, that CHA crystals grow oriented along the collage fibres (43)(44)(45)(46);. However, according to Davies (47), no unambiguous bonding mechanism has yet been proposed.…”

Section: Mechanism Of Bonding To Living Tissuesmentioning

confidence: 99%

Vidrios y Vitrocerámicos Bioactivos

Aza¹,

Aza²,

Peña³

et al. 2007

Bol. Soc. Esp. Ceram. Vidr.

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Since the late 1960´s, a great interest in the use of bioceramic materials for biomedical applications has been developed. In a previous paper, the authors reviewed crystalline bioceramic materials "sensus stricto", it is to say, those ceramic materials, constituted for non-metallic inorganic compounds, crystallines and consolidates by thermal treatment of powders at high temperature. In the present review, the authors deal with those called bioactive glasses and glassceramics. Although all of them are also obtained by thermal treatment at high temperature, the first are amorphous and the second are obtained by devitrification of a glass, although the vitreous phase normally prevails on the crystalline phases.After an introduction to the concept of bioactive materials, a short historical review of the bioactive glasses development is made. Its preparation, reactivity in physiological media, mechanism of bonding to living tissues and mechanical strength of the bone-implant interface is also reported. Next, the concept of glass-ceramic and the way of its preparation are exposed. The composition, physicochemical properties and biological behaviour of the principal types of bioactive glasses and glass-ceramic materials: Bioglass Vidrios y Vitrocerámicos BioactivosDesde finales de los años sesenta, se ha despertado un gran interés por el uso de los materiales biocerámicos para aplicaciones biomédicas. En un trabajo previo, los autores hicieron una revisión de los denominados materiales biocerámicos cristalinos en sentido estricto, es decir, de aquellos materiales, constituidos por compuestos inorgánicos no metálicos, cristalinos y consolidados mediante tratamientos térmicos a altas temperaturas. En el presente trabajo, los autores revisan el desarrollo de los vidrios bioactivos (biovidrios) y de las vitrocerámicas bioactivas. Si bien todos ellos son obtenidos también por tratamiento térmico a altas temperaturas, los primeros son amorfos y los segundos son obtenidos por desvitrificación de un vidrio, si bien la fase vítrea normalmente predomina sobre las fases cristalinas. Después de una introducción al concepto de material bioactivo, se expone una breve revisión histórica del desarrollo de los vidrios bioactivos. A continuación se describe su obtención, reactividad en suero fisiológico artificial, mecanismo de unión al tejido vivo y resistencia mecánica de la interfaz hueso-implante. Posteriormente, se expone el concepto de material vitrocerámico y el proceso de su obtención así como también se describen los principales tipos de vidrios y vitrocerámicos bioactivos (Bioglass ® , Ceravital ® , Cerabone ® , Ilmaplant ® and Bioverit ® ), sus composiciones, sus propiedades físico-químicas y sus comportamientos biológicos. Finalmente, se lleva a cabo también una corta revisión de los recubrimientos con vidrios bioactivos y de los materiales compuestos (composites) bioactivos así como de los usos más comunes de los vidrios y vitrocerámicos bioactivos.

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“…These conclusions are based largely on histological examinations of the enamel and enamel organ such as those of Marsland (15,16) or on histochemical observations such as those of Symons (31,32). Although a number of reports on the ultrastructure of ameloblasts and their precursors have appeared (12,13,17,22,23,25,33,34), these have been confined to studies on cells from the growing end of teeth and have not offered information regarding maturation processes. The secretory nature of these cells has been indicated by Watson (33) and Reith (25).…”

Section: Introductionmentioning

confidence: 99%

The Ultrastructure of Ameloblasts During Matrix Formation and the Maturation of Enamel

Reith

1961

The Journal of Cell Biology

135

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Ameloblasts from different regions of upper incisors of rats were examined with the electron microscope. During matrix formation, the cells resemble secretory cells. They are extremely long, tightly packed, and show considerable polarity. Nuclei are at the basal end of the cell. Mitochondria are proximal and the Golgi apparatus distal to the nucleus. Ergastoplasm is found in all levels but mainly in the distal end. A terminal bar apparatus separates the distal end of the cell from Tomes's process. Next to this is soft enamel. The next incisal region is a transitional zone in which the ameloblasts separate easily from the enamel. Endoplasmic reticulum is dilated and very obviously in communication with the perinuclear space. Mitochondria are present not only proximal, but also distal, to the nucleus. The next incisal zone consists of cells related to the maturation of enamel. They no longer resemble secretory ceils, but now have more characteristics of transporting cells. Processes from the distal end of the cell are present with mitochondria closely applied to the base of the processes. A considerable amount of intercellular space exists with microvilli projecting into the space. Iron granules appear in these cells, and the ergastoplasmic cisternae are dilated. In the incisal end of this zone, the iron granules form aggregates. The iron finally leaves the ceils to enter the enamel. Free RNP particles and fibrils become more evident after the iron leaves the cells. In the most incisal region, the ameloblasts are further reduced in height. Distal processes are no longer present and fibrils are more conspicuous.

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The development of the hamster lower incisor as observed by electron microscopy

Cited by 117 publications

References 28 publications

In vivo experimentation on rat incisor enamel organs through a surgical window

In vivo experimentation on rat incisor enamel organs through a surgical window

Vidrios y Vitrocerámicos Bioactivos

The Ultrastructure of Ameloblasts During Matrix Formation and the Maturation of Enamel

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