Presence Of Tubules Research Articles

Scanning electron microscopy of tissue changes on the pressure surface of human premolars following tooth movement.

abstract – The pressure side of human, premolars subjected to experimental movement for 5–76 d were studied in the scanning electron microscope. Sham‐operated and untreated premolars were used as controls. In order to study the morphology and occurrence of root resorptions, the organic tissue was removed using 1:2 diamino ethane or sodium hypochlorite and the denuded root surfaces were re‐examined in the scanning electron microscope. Areas of compressed soft tissue were regularly present and the size, shape and number of such zones varied in the experimental groups. Initially, tissue affected by pressure was mainly located in the marginal region and subsequently the mid‐portion of the roots became generally influenced. Removal of hyalinized tissue started shortly after the formation, and during this soft tissue removal the underlying hard tissue was resorbed. Observation of circumferentially removed, coalesced fibers corresponded with the finding of extensively resorbed lacunae in the mineralized tissue beneath. The resorptive processes of the cementum began after 10 d as round cavities measuring about 6 μm. Further resorption in cementum was characterized by numerous small, thin‐walled round lacunae which confluenced into extensive, shallow resorptions after 20 d. Dentin was distinguished by the presence of tubules, and in sites of active resorption removal of mineral crystals had occurred, exhibiting a latticed fiber arrangement.

Light, fluorescence, and electron microscopic studies on the pineal organ of the pike, Esox lucius L., with special regard to 5-hydroxytryptamine.

The pineal organ of adult pikes, Esox lucius L., maintained under normal diurnal conditions, was studied with a combination of light microscopy, fluorescence histochemistry of certain arylethylamines, and electron microscopy. 1. The pineal parenchyma consists of sensory cells, supporting cells, and a third cell type which may be identical with previously described ganglion cells. The nerve fibres constituting the pineal tract were well visible after silver impregnation. 2. The sensory cells are dumb-bell shaped and of the typical teleost pineal photoreceptor type. The cytoplasm contains numerous mitochondria and free ribosomes, well-developed rough endoplasmic reticulum and Golgi complex, and is characterized by the presence of tubules and bundles of fibrils. Large numbers of glycogen granules are occasionally recognized. 3. The supporting cells, showing a conspicuous variation in shape, contain a special type of rough endoplasmic reticulum in the form of large, ribosome-studded cisternae with a finely granular content. 4. Basal prolongations of sensory cells and slender projections from supporting cells converge into neuropil-like formations which probably also contain dendrites of ganglion cells. The presence of synaptic vesicles, synaptic rods and tight junctions indicates a transmission mechanism in these neuropil-like areas. The synaptic vesicles react positively after fixation with a zinc iodide-osmium tetroxide mixture. 5. Fluorescence microscopy of formaldehyde-treated pineal organs revealed an intense yellow fluorescence in the entire parenchyma, particularly in basally located “rosette” formations which may be identical with the neuropil-like areas. Small bundles of adrenaline-containing nerves run in the meningeal connective tissues and give off slender fibres which accompany blood vessels in meninges, in the dorsal sack and in the paraphysis; no fibres were seen to enter the pineal organ. The entire pineal area contain large numbers of mast cells probably storing dopamine. 6. Microspectrofluorometric analysis indicates that the yellow pineal fluorophore is identical with 5-hydroxytryptamine, although the presence of other closely related indoles (e.g. 5-hydroxytryptophan and melatonin) cannot be excluded. 7. Pineal 5-hydroxytryptamine is markedly resistant towards the amine-depleting action of reserpine. It disappears after inhibition of the decarboxylating enzyme. The amine accumulates in the parenchyma when monoamine oxidase is blocked. 8. In spite of the application of special methods for electron microscopic visualization of biogenic monoamines, it was not possible to demonstrate the submicroscopic storage site for 5-hydroxytryptamine. 9. The presence of indoles in the fish pineal is discussed with regard to the role in melatonin synthesis, and with regard to a possible functional relation to some as yet unidentified protein or polypeptide hormone in the sensory (photoreceptor) cells and supporting cells; both show features characterizing an active protein synthesis.

Calcification in the Pulp of Teeth Affected by Pyorrhea, with an Outline of a Method of Demonstrating the Presence of Tubules in the Calcified Portions of Such Pulp

Calcification in the Pulp of Teeth Affected by Pyorrhea, with an Outline of a Method of Demonstrating the Presence of Tubules in the Calcified Portions of Such Pulp