Findings on the alterations taking place in the enamel have demonstrated that they are generally caused by a daily use of highly fluoridated drinking waters. According to that, the Authors have carried out an ultrastructural study on lower incisors of albino rats after administering for 60 days water with a fluorine concentration five times the normal one. The samples, studied under the S.E.M., showed a general slowing of both the deposition and the maturation phase as well as the presence of some hypomineralized areas even after eruption. All this suggested the possibility that the damages observed were not due to the direct effect of fluorine on the enamel, but to the interaction between fluorine and ameloblasts. The Authors have then carried out an ultrastructural study on the enamel organ using the S.E.M. The results showed the presence of a well-evident endoplasmic reticulum, the lack in dense granules during the secretion phase, the lack in ruffle ended webs during the modulation phase, and the mitochondrial damage in the ameloblast. All this could justify the slowing of the enamel mineralization caused by fluorine effect on the ameloblasts.

Ameloblasts↗

PubMedDate not supplied

Atrophy of the soleus muscle in the albino rat induced by immobilization.

The morphological changes in the soleus muscle, immobilized by means of a plaster cast applied to the posterior limb of albino rats was studied. The animals were sacrificed 20 and 30 days after immobilization. The Authors agree with the hypothesis put forth by Lazarides regarding the cytoskeleton model of striated muscle fiber: morphological changes of the sarcomeres and myofilaments are brought on by translateral and longitudinal bridge damage.

Animals↗

PubMedDate not supplied

The shape of enamel crystals as seen with high resolution scanning electron microscope.

The authors have carrie out a study on the shape of apatite enamel crystals by means of field emission S.E.M.; for this purpose the lower incisor enamel of albino rats and the enameloid of fossil remains of Odontaspis from the Cretaceus and Miocene ages were used. The analysis of the available literature showed two different models: according to the first model enamel crystals were elongated hexagonal rods; according to the second, the one of Warshawsky, the enamel crystals were flat ribbons, with a rectangular cross-section. In accordance to the synthetic apatite morphology and to the shape of the unit cell, the authors show that the single enamel crystal is a rod with an equilateral hexagon base.

Animals↗

PubMedDate not supplied

The non-junctional sarcolemmal cytoskeleton: the costameres.

In skeletal muscle fibers the costameres have been defined by Pardo et al. (1983) as transverse circumferential elements of the cytoskeleton associated to the sarcolemma. Since the first immunolocalization, carried out with purified antivinculin antibodies to the present day, about 10 proteins have been located in costameres, as well as some transmembrane proteins of the integrin superfamily. In particular the colocalization of vinculin and talin and the presence of the integrins confers to this system the description of the adherens junctions type cell-ECM, while the presence of dystrophin in correspondence to both A and I bands with Z line negative is important for the stabilization of the membrane of the skeletal muscle fiber. We are therefore of the opinion that costameres can be defined as a real proteic "machinery".

Animals↗