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PubMed1991

[Simplification of the production of plastination histologic preparations through the use of a grinding machine].

A new histological method basing on the plastination technique (v. Hagens, Tiedemann, Kriz 1987) has recently been developed and applied to research in human fetal development. This plastination histology shows some evident advantages compared with the classical histological techniques. As the application of this new method has been very time consuming up to now, only some special questions of basic research have been investigated. We here present the use of a grinding-machine, which can be used to partially mechanize the procedure of plastination histology.

Aged↗
PubMed1991

Laboratory evaluations on thermal debonding of ceramic brackets.

The purpose of this laboratory study was to define the working parameters and physiological safety and efficacy of the Dentaurum Ceramic Debonding Unit. Extracted mandibular incisors were utilized because of their low thermal mass and low heat sensitivity. The teeth were embedded in plastic and placed on a turning force measuring apparatus. An electrothermal element was placed in the pulp chamber (filled with a conducting paste). The thermoelement temperature was registered on y-t recorder as was the turning momentum required to remove the ceramic brackets with the Dentaurum Ceramic Debonding Unit. Ceramic brackets from GAC (Allure III), Unitek (Transcend) and Dentaurum (Fascination) using one and two component adhesives (Monolok, Concise), were tested. Scanning electron microscopic views taken after debonding showed predictable (and favorable) adhesive failure at the bracket base/resin interface. No enamel damage was demonstrated. All brackets were removable under three seconds with a clinically reproducible turning force of 85-100 Nmm allowing for intrapulpal temperature increases under the 5 degrees C biocompatible threshold. The Dentaurum Ceramic Debonding Unit provided a safe, reliable, efficient modality of removing ceramic brackets while maintaining a physiologically acceptable rise in pulpal temperature without damage to tooth enamel or pulpal tissue.

Body Temperature↗
PubMedDate not supplied

[Morphologic aspects of the vestibular nerve of the chinchilla].

A quantitative study was made of the number of fibers, their diameters and patterns of distribution in 14 ampullar nerves of chinchilla. The nerves were processed for osmium staining, embedded in plastic and cut serially in 1-micron-thick sections for histologic evaluation. Quantitative evaluation of nerve-fiber characteristics was made with the aid of a laboratory computer and specific programs. The number of the nerve fibers ranged between 1,877 and 2,175. The diameters of the fibers could be as large as 8 microns. The fibers between 2 and 2.5 microns were the most abundant, representing 29.6% of the fiber population. The distribution of fibers in the cristae was size-dependent: 80% of the thin fibers were located at the ends of the nerves, while most of the thick fibers were distributed through the central and intermediate areas.

Animals↗
PubMed1990

[Ultrastructural alterations of Golgi tendon organs in disuse atrophy induced by muscle immobilization in rats].

In order to investigate changes in the ultrastructure of Golgi tendon organs (GTOs), the leg muscles of Wistar strain rats were immobilized over various periods. The immobilized triceps surae muscles were divided into three categories: a stretched-position group, a relaxed-position group, and Achilles tendon tenotomy group. After 1, 2, 3, 4, 6 and 8 weeks the muscle preparations dissected from the muscle belly and from the muscle-tendon junction were processed for classification of the fiber type histochemically and to find GTOs in plastic embedded-preparations. In the Achilles tenotomy group, an early fiber transformation from type I to type II fiber was observed, but in the other two groups a low rate of transition of fiber type occurred. At the end of 8 weeks, similar tendencies were observed in all groups. The ultrastructures of GTOs were not significantly different among three groups in basic and general structure when compared with the control group. However, swollen mitochondria in axons and axon terminals and damage in the lamina structure of the myelin sheath were seen in the capsule, axon terminal, and myelinated nerve fiber of GTOs. Although some differences were observed with shorter periods of immobilization, several structural changes were observed over longer periods, indicating the more profound effect of the length of the period rather than the type of immobilization.

Animals↗
PubMed1990

Glomerular volume in type 2 (noninsulin-dependent) diabetes estimated by a direct and unbiased stereologic method.

Glomerular volume was estimated in 20 type 2 diabetic patients (age 64 +/- 6 years, duration of diabetes 6 +/- 5 years) compared with 14 sex- and age-matched controls, as well as in a group of 11 very long-term type 1 diabetic patients (age 61 +/- 12 years, duration of diabetes 44 +/- 11 years). One whole autopsy kidney was obtained prospectively, and a known fraction (approximately equal to 1/140) was sampled systematically and embedded in plastic (JB-4 glycolmetacrylate), thereby essentially eliminating shrinkage. Sections 15-microns thick were stained with periodic acid-Schiff. Mean glomerular volume was estimated on a random sample of glomeruli using the disector method. Frequency of glomerular occlusion and mean volume of open glomeruli was estimated. Mean glomerular volume was not different between type 2 diabetic patients and controls (5.3 +/- 1.7 M mu3/1.73 m2 versus 5.3 +/- 1.9 M mu3/1.73 m2) nor was total glomerular volume or kidney weight. Frequency of glomerular occlusion was 4.8 +/- 5.7% in controls, 8.9 +/- 7.8% (p = 0.10) in type 2 patients, and 16.8% +/- 20.7 (p less than 0.05) in type 1 patients. In type 2 patients there was a correlation between frequency of glomerular occlusion and mean volume of open glomeruli (r = 0.44, p = 0.05), and the same tendency was seen in type 1 patients (r = 0.49, p = 0.12). By the present method the absolute level of glomerular volume was increased by at least a factor of two compared with previous studies. This illustrates the problems arising from shrinkage of tissue in paraffin and stresses the importance of using an unbiased stereological method. The lack of increase in total glomerular volume is in accordance with clinical findings of lack of glomerular hyperfiltration in type 2 patients, findings in contrast to those in type 1 diabetes. It is suggested that hyperfiltration per se is not the cause of glomerulopathy.

Aged↗
PubMed1989

Development of the retinal tapetum lucidum of the walleye (Stizostedion vitreum vitreum).

The development of the retinal tapetum lucidum within the cells of the retinal pigment epithelium (RPE) has been investigated by both light and electron microscopy in the walleye (Stizostedion vitreum vitreum) in specimens ranging in total length from 25-140 mm. In addition changes in the arrangement of the photoreceptors (both rods and cones) in both light and dark-adaptation have also been studied. At 25 mm no evidence of a tapetum is present. At about 30 mm it makes its initial appearance as granular bodies formed within the apical smooth endoplasmic reticulum (SER) cisternae of the RPE cells in the superior temporal fundus. The developing tapetum then spreads peripherally and continues to thicken in existing areas. By 90 mm it is well established throughout the fundus but always appears better developed in the superior fundus. By 125-140 mm it is essentially adult in appearance. At 60-70 mm the rods and cones begin to form bundles producing macroreceptors of 20-30 photoreceptors. In dark-adaptation the rod bundles are retracted and have one or more cone cells centrally located in each bundle, with the bundles separated from one another by melanosomes. Initially when no tapetal material is present, post-larval walleye are positively phototactic and feed on zooplankton. In the adult condition when a tapetum lucidum and large macroreceptors are present, the walleye is negatively phototactic and feeds almost exclusively on larger organisms such as other fish.

Adaptation, Ocular↗
PubMed1989

Photoreceptor fine structure in the bobtail goanna (Tiliqua rugosa).

The fine structure of the retinal photoreceptors has been studied by light and electron microscopy in the bobtail goanna (Tiliqua rugosa) an Australian diurnal lizard. The photoreceptors in this species are readily divisible into rods or cones based on morphological criteria. Single cones are the dominate cell type with a cone:rod ratio of about 80:1. No multiple photoreceptors were present nor was a photoreceptor mosiac observed. Cones are large cells with a short, tapering outer segment. The inner segment contains a large apical oil droplet, an ellipsoid of mitochondria and a prominent paraboloid of glycogen. Rods are slender cells with a longer non-tapering outer segment. Rod inner segments display an ellipsoid but no oil droplet or paraboloid. The nuclei of cones are large and vesicular while rod nuclei are smaller and displayed more heterochromatin. The synaptic pedicle of cones is larger than the spherule of rods. Both rods and cones displayed both invaginated (ribbon) and conventional synapses with the large cones having more synaptic sites. As only light-adapted specimens were examined it is uncertain if either rods or cones are capable of retinomotor responses.

Animals↗
PubMed1989

Fine structure of the conus papillaris in the bobtail goanna (Tiliqua rugosa).

The structure of the conus papillaris in an Australian lizard, the bobtail goanna (Tiliqua rugosa) was investigated by light and electron microscopy. In this strongly diurnal species, the conus papillaris consists of a heavily vascularized and pigmented, finger-like structure about 1 mm in diameter and 3-4 mm in length. It is situated over the optic nerve head and projects into the vitreous chamber. Within the conus are numerous capillaries and larger blood vessels, melanocytes and occasional mast cells. Many of the capillaries display prominent luminal and abluminal microfolds. Other capillaries show no microfolds while still others display an intermediate number of microfolds. The larger blood vessels are usually indistinguishable as to being either arterioles or venules. The endothelial cells of all blood vessels show a population of cytoplasmic granules. The melanocytes are large pleomorphic cells usually rich in microfilaments. Unmyelinated nerve processes are plentiful within the conus and the Schwann cells enclosing these nerve fibres are occasionally seen to be pigmented. The morphology of the conus papillaris indicates a heavy involvement in the transport of materials. It is considered to be homologous to the pecten oculi of the avian eye; to the falciform process of the teleost eye; to the supraretinal vessels of amphibians and to the intraretinal vessels of the mammalian eye.

Actin Cytoskeleton↗
PubMed1989

Retinal pigment epithelial fine structure in the bobtail goanna (Tiliqua rugosa).

The retinal pigment epithelium (RPE), the choriocapillaris and Bruch's membrane (complexus basalis) have been studied by light and electron microscopy in the bobtail goanna (Tiliqua rugosa) an Australian diurnal lizard. The RPE consists of a single layer of cuboidal cells which display very deep and tortuous basal (choroidal) infoldings as well as numerous apical (vitreal) processes which interdigitate with the photoreceptor cells. The lateral cell borders are relatively smooth and joined by basally located tight junctions. Internally smooth endoplasmic reticulum is abundant while rough endoplasmic reticulum is not. The RPE cell nucleus is large and vesicular and basally located in the light-adapted state. Polysomes, mitochondria and myeloid bodies are present and widely distributed. Melanosomes are plentiful in the apical region of the epithelial cells in light-adaptation. Bruch's membrane is pentalaminate with the basal lamina of the choriocapillaris being exceptionally thick. The choriocapillaris is a single layer of large-caliber capillaries with thin but only moderately fenestrated endothelium. Numerous dense granules are always present within these endothelial cells.

Animals↗
PubMedDate not supplied

Failure of propranolol to prevent chronic hyperthyroid induced cardiac hypertrophy and multifocal cellular necrosis in the rat.

The effect of excess thyroid and thyroid plus propranolol on right and left ventricular structure was examined. Perfusion fixed hearts from untreated adults and those treated for 10 weeks with thyroid, propranolol, and thyroid plus propranolol were embedded in plastic and sectioned for light and electron microscopy. Hyperthyroidism stimulated a significant increase in heart rate, oxygen consumption, and systolic blood pressure. Propranolol was effective in normalizing the heart rate of hyperthyroid rats, but did not affect oxygen consumption or blood pressure. Both left and right ventricular weight increased similarly in thyroid and thyroid-propranolol treated animals, but right ventricular mass increased more than left ventricular mass in both groups. The majority (21 of 24) of right ventricles from thyroid and thyroid-propranolol treated animals had multifocal areas of histologically detected fibrosis. Left ventricular fibrosis was absent or minimal in both hyperthyroid groups. Neither left nor right ventricular fibrosis was observed in control or propranolol only treated animals. We conclude that beta adrenergic stimulation is unnecessary for thyroid induced cardiomegaly, and excess thyroid hormones induce right ventricular fibrosis which is not prevented by propranolol.

Animals↗
PubMed1988

Relative growth rates of maxillary mesenchyme in the chick embryo.

Chick embryos were injected with [3H]-thymidine at days 3-7 of incubation and were fixed and embedded in plastic. The embryos were divided into three stage groupings of development [Hamburger and Hamilton: J Morphol 88:49-92, 1951], and labeling indices were determined for each of the following delineated regions within the maxillary process at each stage: region 1, subepithelial mesenchyme located at the medial side of the maxillary process adjacent to the roof of the stomodeum; region 2, subepithelial mesenchyme at the ventral tip of the maxillary process (as seen on cross section); region 3, subepithelial mesenchyme at the lateral portion of the maxillary process below the eye; and region 4, interior mesenchyme defined as the central portion of the maxillary process and separated from the epithelium by the three other regions. Results indicated that differences exist among the regions examined and that these differences were stage specific. At stages 19-21 and stages 24-25 1/2, growth rates were higher in subepithelial regions than interiorly. At stages 28-29, however, a statistically significant difference among the regions was not found. These results suggested that there is an association between growth rates in the maxillary process mesenchyme and its proximity to the overlying epithelium and that these effects are related to the stage of development.

Animals↗
PubMed1988

[A lidocaine base for surface anesthesia of the tympanic membrane].

An anatomical study was conducted to determine the effects of 10% lidocain base (dissolved in DMSO) on the structure of the tympanic membrane. Survival times ranged from 1 day to 3 months. Membranes were embedded in plastic and cut in semithin sections. Within 1 and 3 days mild swelling of the epithelium was seen; 1 month after treatment the connective tissue layers of the lamina propria were severely hyperplastic. 2 months after lidocain-Base application additional collagen fibres, loosely packed and less regularly, appeared in the submucosal connective tissue layer. However, normal appearance of the drums was noticeable after 3 months survival.

Anesthesia, Local↗
PubMed1987

Cell-specific regulation of neuronal production in the larval frog retina.

We have previously postulated the existence of a feedback mechanism from differentiated neurons that regulates the production of new neurons. Evidence for such regulatory feedback comes from experiments in which dopamine-containing amacrine cells, ablated in the developing retina by 6-hydroxydopamine (6-OHDA), were up-regulated in their production. To determine whether this is a general phenomenon of the developing retina, the neurotoxin kainic acid (KA) was injected intraocularly in midlarval-stage Rana pipiens tadpoles to produce selective lesions of certain retinal cell types. After periods of 1-21 d, the animals received intraperitoneal injections of 3H-thymidine. Animals were then allowed to survive for periods of up to 3 weeks and were then fixed, the eyes embedded in plastic, sectioned at 3 micron, and processed for autoradiography by standard methods. At the dosage used, the KA produced a 52% decline in the cell density of the inner nuclear layer (INL), a 37% decline in the retinal ganglion cell layer (RGC), and no significant change in the density of cells in the outer nuclear layer (ONL). The 3H-thymidine allowed us to detect any changes in the number of new cells added to the retina after the KA lesion. Within the first week after the KA injection, there was a decrease in the number of 3H-thymidine (3H-Thy)-labeled cells in the lesioned eye as compared to in the control retina; however, KA treatment of slice cultures demonstrated that the toxin does not affect proliferating neuroblasts directly.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Presence of alkaline-phosphatase-positive reticulum cells in fetal liver and bone marrow of mice and their absence in yolk sac.

One of the conspicuous stromal cells in hematopoietic parenchyma of the bone marrow in adult mice is the alkaline-phosphatase-positive reticulum cell (A1-RC). To determine whether it is present in the fetal yolk sac, liver, and bone marrow of mice, these tissues were examined at the gestational ages when they are sites of hematopoiesis. Fetuses of nine, 16 and 18 days of gestation were fixed and embedded in plastic, and 2-micron sections were stained for alkaline phosphatase and examined by light microscopy. No cells with the characteristics of the A1-RC were seen in the blood islands of the yolk sac, the site of erythropoiesis. Because of the high resolution of this method, however, alkaline phosphatase activity was observed on the border of the adjacent endodermal cells for the first time. By 16 days, the liver contained A1-RC interspersed with hematopoietic cells, as well as alkaline phosphatase activity in bile canaliculi. We found that the A1-RC is the predominant stromal cell of bone marrow at 18 days of gestation. We conclude that, as maturation proceeds, the hematopoietic stromal environment becomes more similar to that of the adult.

Alkaline Phosphatase↗
PubMed1985

Aluminium-induced osteomalacia in severe chronic renal failure (SCRF).

In patients with severe chronic renal failure (SCRF), especially in those undergoing chronic dialysis, aluminium may accumulate in the body. The aluminium is derived from the dialysate and/or from orally-administered, aluminium-containing phosphate binders. Accumulation preferentially occurs in the bone causing aluminium-induced osteomalacia. The physiopathological mechanisms of the disease still have to be elucidated. It has been suggested that aluminium accumulates at the osteoid/calcified-bone boundary (OCBB) inhibiting the influx of calcium there, and also that aluminium directly suppresses the secretion of parathyroid hormone (PTH). A third factor inducing the mineralization defect may be the presence of aluminium within the mitochondria of the osteoblast. In accordance with these hypotheses, hypercalcemia and relatively low iPTH levels are frequently found in aluminium-induced osteomalacia. Histologic methods are essential for demonstrating the actual existence of aluminium-induced osteomalacia. A large bone biopsy is desirable. When the biopsy is not decalcified and embedded in plastic, excellent histologic pictures are obtained wherein mineralized and non-mineralized bone (i.e. osteoid) can be distinguished clearly. Furthermore, the un-decalcified sections can be stained for aluminium, iron or both, and they are suitable for evaluation of the bone marrow status. Several features, like irregularly distributed osteoid with variable thickness, a relatively low number of cubic osteoblasts, and the absence of marrow fibrosis, are suggestive of aluminium-induced osteomalacia. However, the latter can only be proven by histochemical methods, e.g. by the aluminon staining. The treatment of aluminium-induced osteomalacia is quite different from that of other types of renal bone disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum↗
PubMed1985

Ultrastructure of normal epiphyseal cartilage of the articular-epiphyseal cartilage complex in growing swine.

Normal epiphyseal cartilage from the articular-epiphyseal cartilage complex (A-E complex) of the distal parts of the femur and humerus of growing commercial crossbred boars was collected, embedded in plastic, and studied by light and electron microscopies. The morphology of this cartilage was determined to provide a basis for comparison with cartilage affected with osteochondrosis, an important clinical disease in swine. Normal epiphyseal cartilage from the A-E complex in growing swine was divided into 4 major regions of cells: resting, proliferating, hypertrophic, and calcifying regions. Cells in the resting zone contained prominent lipid and densely aggregated glycogen. As the cells proliferated and matured, the lipid and glycogen became less prominent. The lipid droplets became smaller and scarcer, and the glycogen became dispersed in the cytoplasm. Proliferating and hypertrophic cells clustered in roughly egg-shaped groups of 4 to 8 cells/plane of section. In the calcifying region, the interterritorial matrix (between cell clusters) calcified, and the territorial matrix (uniting cells in a cluster) remained uncalcified. Calcified matrix extended the depth of one cell group from the area of capillary penetration, and the capillaries invaded by entering a cluster of cells. Territorial matrices in all regions of A-E complex epiphyseal cartilage were composed of randomly oriented collagen fibrils with a granular fibrillar proteoglycan network dispersed between the fibrils. Heterogeneity of chondrocytes was characterized by the presence of both light- and dark-staining cells in the proliferating through calcifying regions and by 3 morphologically distinct light cell types in the late hypertrophic and calcifying regions.

Aging↗
PubMed1985

Cerebellar foliation in rats. 1. Cortical changes preceding the formation of a fissure.

The cerebellar cortices of foetal rats were examined for structural changes occurring prior to the formation of fissures. Female rats were mated overnight and the first day on which a sperm-positive vaginal smear was found was designated as embryonic day 1 (E1). Birth of rats generally occurs on day E23. Foetuses from days E19 to 22 were fixed by perfusion followed by immersion, using a mixture of glutaraldehyde and paraformaldehyde, and their cerebella embedded in plastic. The cerebella of thirty-five foetuses were sectioned sagittally at intervals of 100 micron, and those of five were sectioned coronally. A continuous Purkinje cell layer was formed during the examination period by fusion of four transverse bands. The study revealed formation of pre-migratory granule cells in the EGL of foetal rats. The granule cells were orientated in the coronal plane and were seen only where Purkinje cells were present beneath the EGL. A local increase in pre-migratory granule cells and indentation of the Purkinje cell layer were early signs of foliation and occurred prior to the formation of a fissure. The subsequent deepening of the fissures was due to the outward expansion of lobules, and the bottom of the different fissures retained their spatial relationship. The findings show that the expansion of the cerebellar surface is tangential before and after the formation of a fisure. In order to indent the surface, the direction of the expansion must change temporarily. This reorientation of the expansion appears to be related to the cortical changes which have been described and marks the onset of foliation.

Animals↗
PubMed1972

Human intracranial atherosclerosis. A histochemical and ultrastructural study of gross fatty steak lesions.

A descriptive study of atherosclerotic lesions in human intracranial arteries was undertaken using both light and electron microscopic technics. Arterial segments of human middle cerebral, internal carotid and basilar arteries with gross fatty streak lesions were obtained at autopsy within 4 hours after death, fixed and embedded in plastic. A new technic has been developed in which 0.5 mu-thick sections can be stained with PAS/alcian blue, thereby enabling clear differentiation, substantiated by simultaneous electron microscopic studies, between the lipid-filled smooth muscle cell, which is surrounded by a PAS-positive basement membrane, and the lipid-filled blood monocyte. These technics demonstrated that the gross fatty streak comprised a focal intimal thickening bordered on the lumen by a patent endothelial lining and on the media by a usually intact elastic membrane. The lesion contained smooth muscle cells and cells presumed to be blood monocytes, both filled with and devoid of lipid droplets. Although little fragmented or new elastica was found in the extracellular space, numerous foci of membranous material could be observed, believed to be cell debris and plasma lipoproteins. The similarity between the morphology of such lesions in intracranial arteries with those found in other arterial beds suggests that the documented differences in the prevalence of atherosclerosis in the various beds has no bearing on either the structure of each type of lesion or its progression.

Adult↗