Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Plastic Embedding”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,099 records · Page 61Linked to original sources
PubMed2003

Osteotomy with 80-micros CO2 laser pulses--histological results.

Haemostatic and aseptic effects and intricate cut geometry are beneficial aspects of non-contact laser osteotomy. Collateral thermal damage, however, has severely limited the use of conventional lasers. The purpose of this study was to test the side effects on bone after cutting it with short CO2 laser pulses and simultaneous application of a fine air-water spray. The 10.6 microm CO2 laser emitted 80 micros pulses of 46 mJ energy, f=100 Hz, focused to a spot diameter of 130 ìm. Scan rate amounted to 40 mm/s. To approximate live conditions 10 samples of cortical bone and 10 rib segments were prepared immediately after sacrificing of pigs. A reference cut with a bandsaw and three laser cuts with an increasing number of beam passes (4, 16, 64) were performed on each sample. Half of the samples were decalcified in EDTA. The others were embedded in plastic to cut non-decalcified sections. The laser incisions were not accompanied by carbonisation. The incisions with slightly convergent walls were 150 ìm wide. The depths of the cavities increased with the number of the beam passes from approximately 0.5 mm (4 passes) to 3 mm (64 passes). At the border of the incisions two narrow zones of damage were noted: an amorphous intensively stained zone of 1-3 microm width and a wider, also sharply demarcated but faintly stained zone of 7-10 microm. A broader zone of about 50 microm was characterised by empty lacunae and osteocyte damage. These effects were not predictable; intact osteocytes were also observed near to the cut surface. Polarised light microscopy showed no alterations in the inorganic structure of the bone at the cut borders. The histological results indicated only minimal damage to bone ablated at the specified parameters. The described laser procedure might have advantages over mechanical instruments.

Animals↗
PubMed1986

Hepatic involvement in systemic mast cell disease.

Thirteen patients with systemic mast cell disease were studied in order to define the hepatic changes in this disease and to correlate the histologic lesions in the liver with the clinical findings. These patients often presented with multisystem disorders and 10 had hepatomegaly. Microscopically, the liver tissues in all patients showed fibrosis and chronic inflammatory cellular infiltration with plasma cells, lymphocytes, eosinophils, and mononuclear fibroblast-like cells in the portal area. The hepatic sinusoids were not significantly involved. A histologic diagnosis of systemic mast cell disease is seldom entertained in liver biopsy specimens embedded in paraffin and stained with hematoxylineosin, but can be facilitated in biopsy specimens embedded in plastic such as methacrylate. Tissue mast cells in the cellular infiltrate can be demonstrated best by special staining techniques with Giemsa, toluidine blue, and chloroacetate esterase. The severity of the histologic changes in the liver does not correlate well with the size of the liver or biochemical changes in the blood. Abnormal serum biochemical values were noted primarily in those with dehydration caused by diarrhea and vomiting, and in those with malnutrition. Hepatic function test results were usually normal, except for alkaline phosphatase level, which was elevated in all 13 patients. Although the clinical significance of hepatic involvement in systemic mast cell disease cannot be established with certainty in this study, it is believed that the prognosis of systemic mast cell disease is most intricately related to the systemic effects of mast cell involvement in many other organs, and not to hepatic involvement per se.

Adult↗
PubMed1993

Total number of particles in a bounded region estimated directly with the nucleator: granulosa cell number in ovarian follicles.

OBJECTIVE: Our objective was to evaluate the precision of the "nucleator" with regard to estimation of the number of granulosa cells in individual follicles and the average number of granulosa cells per follicle in a group of follicles. STUDY DESIGN: Nine murine ovarian follicles embedded in plastic were oriented isotropically with the "orientator" by Mattfeldt, cut into 20 microns serial sections, and stained with hematoxylin. In each follicle the number of granulosa cells was estimated in two ways, both unbiased: (1) with the nucleator principle in the section that contains the nucleolus of the oocyte and (2) in the complete set of follicle sections with the "fractionator" principle. Estimates with the fractionator were interpreted as "true" values. Therefore the precision (CE) of the nucleator estimates could be calculated. RESULTS AND CONCLUSION: The nucleator provides precise estimates of the number of granulosa cells in one complete follicle: CE = 0.12. The amount of effort is minimal, because estimation is based on roughly 50 granulosa cells. The precision of the procedure with regard to estimation of the average number of granulosa cells in a group of follicles depends mainly on the biologic variation (CVbiol = 0.71).

Animals↗
PubMed1986

Peptidergic nociceptive axon visualization in whole-mount preparations of cornea and tympanic membrane in rat.

A whole-mount preparation is described for visualizing unmyelinated peptide immunoreactive axons in two specialized tissues, thin enough for tracing axons to their terminal knobs. These tissues, the cornea and the mucosal surface of the tympanic membrane, are known to possess specialized nociceptor innervation and can be used for selecting sensory endings labeled by peroxidase reaction product and embedded in plastic for more detailed analysis. Rat calcitonin gene-related peptide antibody proved a particularly robust primary antibody found in a substantial proportion of sensory unmyelinated axons in a variety of fixation and preparative conditions.

Animals↗
PubMed1988

Changes in inner plexiform layer thickness following neonatal visual cortical ablation in cats.

The effect of visual cortex removal at 5-7 days of age on the development of the inner nuclear and inner plexiform layers of the cat's retina was examined in animals which had survived 9-36 months after the cortical removal. The lesions were unilateral so that only the nasal or the temporal region of each retina was affected, and the affected regions were positively identified by HRP injection into the optic tract either ipsilateral or contralateral to the ablated hemisphere. Small sections of retina straddling the naso-temporal boundary were then embedded in plastic and sectioned radially for analysis. In this way, comparisons could be made between areas of retina which were closely matched in terms of location as well as histological history. Cells in the inner nuclear layer in affected regions of retina appeared normal both in number and size, even though ganglion cell density in these areas was clearly reduced. This indicates that, at least at this age, the survival of inner nuclear layer cells does not depend on the availability of ganglion cells as synaptic targets. Paradoxically, in the affected regions of retina there was an increase in the width of the inner plexiform layer which was not associated with any change in the thickness of other, more distal retinal layers. This could be due either to an increased growth of surviving ganglion cells and/or inner nuclear layer cells, or to an increase in the survival of cells in the ganglion cell layer, perhaps displaced amacrine cells, which have a greater dendritic volume than the lost ganglion cells.

Animals↗
PubMed1992

Dorsal root potentials and afferent input to the spinal cord in rats with an experimental peripheral neuropathy.

Compound action potentials (CAPs), dorsal root potentials (DRPs) and cord dorsum potentials evoked by stimulating the sciatic nerves have been measured in 4 control rats and in 19 rats with a constriction injury of one sciatic nerve produced by loose ligation of the nerve at mid-thigh level 5 days (n = 8) or 10 days (n = 11) before the acute experiments. The contralateral nerve was exposed but not ligated in a sham procedure. In all cases, the nerve was stimulated proximal to the lesion. At 5 days post-operative (PO) the maximal A-fibre CAPs on the nerve-injured side were not significantly different from those on the sham-operated side. At 10 days PO all animals showed a decrease in the CAP on the nerve-injured side. The mean CAP area on the nerve-injured side was 74.0% +/- 4.2 of the sham-operated side, which was significantly different (P less than 0.005). The sciatic nerves and L5 dorsal roots from 4 of the 10 day PO animals were examined histologically and showed no signs of demyelination or degeneration. The amplitude and area of the maximal DRPs were significantly smaller on the nerve-injured side than on the sham-operated side in all of the nerve-injured animals (P less than 0.01 at 5 days PO; P less than 0.05 at 10 days PO). The mean area of DRPs from the nerve-injured side was 61.7% +/- 10.1 and 46.8% +/- 7.5 of the DRPs from the sham-operated side in the 5 and 10 day PO animals, respectively. The DRPs evoked by sub-maximal afferent volleys were also measured. In all of the nerve-injured animals the CAP-DRP curve on the nerve-injured side was shifted to the right compared to that of the sham-operated side, such that a given size of CAP evoked a smaller DRP on the nerve-injured side than on the sham-operated side. We conclude that the constriction injury produces a decrease in the DRP generated by a volley in the injured nerve and that this change is independent of the decrease in the CAP seen in the injured nerve. We propose that the constriction injury affects the central mechanism responsible for generating primary afferent depolarization (PAD), and thus the pre-synaptic inhibitory control of the afferent input from the injured nerve is impaired.

Action Potentials↗
PubMed1995

The organisation of the axonal reticulum at a ligation, in in vitro incubated bovine splenic nerves.

From previous studies we concluded that in noradrenergic neurons the axonal reticulum can be considered to be an extension of the Golgi apparatus, directly involved in the condensation and packaging of neurosecretion. But the precise ultrastructure of the organisation of the axonal reticulum in relation to neurosecretory granule formation remained to be elucidaded. This conversion was studied in ligated bovine splenic nerve incubated in vitro for three hours. The ultrastructure of the material accumulating proximally and distally was examined and its nature was determined by phosphotungstic acid staining and immunocytochemistry on glycolmethacrylate sections. Proximal to the ligation predominantly electron-lucent vesicles and tubules were found. Tubules of intermediate electron density appeared in between. The latter, especially in thicker sections, were seen to form complexes with tubules and granules of high electron density. All those elements were shown to be positive for dopamine-beta-hydroxylase and cytochrome b561. In the distal part multivesicular bodies accumulated and they were also positive for both enzymes. From these findings it is concluded that the different types of structures accumulating proximally belong to a neurosecretory axonal reticulum. At a block the axonal reticulum is triggered to generate a reticular differentiation, in which granular densities of different size are found. This configuration compares well with that in nerve terminals and strongly suggests that granule formation is basically a local process.

Animals↗
PubMed1996

Time scale and extent of neuronal and synaptic loss in the hippocampal formation of malnourished adult rats.

We have demonstrated that a prolonged low-protein diet induces neuronal and synaptic loss in the hippocampal formation of the adult rat. Because 6 months of protein deprivation was the shortest period analyzed in the previous investigations, in the present study we have evaluated the length of the treatment period necessary to induce significant changes in the numbers of neurons and synapses. Groups of 2-month-old rats were analyzed: (1) and (2) malnourished for 1 and 3 months with a low-protein diet (8% casein): (3) and (4) age-matched control rats fed with a standard diet. Stereological methods were employed to estimate the total number of granule, hilar, CA3 and CA1 pyramidal cells and the volume of the respective cell layers, the volume of the mossy fiber system and the number and related quantitative features of mossy fiber-CA3 synapses. No differences in the number of cells or synapses were found between 1-month malnourished rats and the respective controls. However, in rats treated for 3 months the total number of granule cells. CA3 and CA1 pyramidal cells was reduced, as was the total number of synapses. These findings indicate that the changes induced by protein deprivation progressively increase during the early phases of treatment and that they are already evident after 3 months of protein deprivation.

Animals↗
PubMed1986

Three-dimensional reconstruction from serial sections. IV. The reassembly problem.

In many fields of biology and medicine there is a pressing need for quantitative descriptions of biological structures at a resolution of micrometers. This need is currently met best by three-dimensional reconstruction from serial sections. The preliminary steps in three-dimensional reconstruction include fixation, embedding in plastic, introduction of fiducials, serial sectioning, and staining. At the light microscope level, with which we are chiefly concerned, one will usually want to do photomicrography (or videomicrography) of adjacent fields within individual tissue sections. The resultant images are projected onto a digitizer pad and the contours of interest manually digitized. From the digitized coordinates generated thereby, one wishes to generate a likeness of the original object, using computer graphic displays, and to then do interactive morphometrics. The problem of combining the digitized coordinates so as to produce a numerically faithful representation of the original object (i.e., the reassembly problem) is, as a practical matter, nontrivial. A technical description of the reassembly problem is presented. The main factors entering into a solution of the problem are discussed and a mathematical statement of the solution is given.

Anatomy↗
PubMed1986

Three-dimensional pattern of ductuloacinar associations in normal and pathological human pancreas.

To explain the changes that must occur to produce the characteristic lesions of chronic calcifying pancreatitis, a three-dimensional reconstruction of pancreatic ductules and acini has been undertaken in normal subjects and in patients presenting with disease. This has been done with 3-micron serial sections of tissue embedded in plastic. Two approaches were used. In the first, ductules were reconstructed along with the acini directly associated with them. Using this method, adhesions or anastomoses between acini were not evident in normal specimens, and the quantity of acini associated with the ductules seemed small. The second method involved tracing the association of acini and ductules, beginning in the periphery of lobules, with the aid of a drawing tube. It became evident that an acinus was not necessarily the termination of the glandular system, but that intercalated ducts could be formed on the other side of the acinus, extending the quantity of acinar contributions that could be made to a primary ductular system. Evidence of dilation of ducts, atrophy of acini, formation of cul-de-sacs, and localized obstruction were found by three-dimensional reconstruction of serial sections from patients with chronic pancreatitis along with anastomosis between acini. It is probable that anastomosis becomes more detectable in patients as duct lumina enlarge. Anastomoses in the ductules in chronic pancreatitis may result from loss of some lobular structures, emphasizing preexisting connections or fusions of pancreatic elements, or both, as part of the pathological process.

Adult↗
PubMed1988

Gonadotropin-induced ovulation in a reptile (Anolis carolinensis): histological observations.

Although much is known about morphological changes in the apex of the mammalian ovarian follicle prior to its rupture (ovulation), information about this process in nonmammalian vertebrates is limited to only a few species. We describe here the histological changes in the stigma of the lizard (Anolis carolinensis) ovarian follicle preceding FSH-induced ovulation. Females with a large vitellogenic follicle received two injections, separated by 7 hr, of either porcine FSH (25 micrograms) or saline, and then were sampled at 6, 9, 12, 15, 18, and 24 hr after the first injection. Thus, all but the 6-hr group received two injections. By 12 hr, about half of the FSH-treated females had ovulated, and most had ovulated by 15 hr. In contrast, only 1 of 40 control females ovulated. Large unovulated follicles were fixed and bisected through the circular stigma; one hemisphere was embedded in paraffin and stained with Mallory's trichrome, and the other was embedded in plastic and stained with toluidine blue. FSH treatment produced marked histological changes in the stigma region, as well as alterations in nonstigmal areas of the follicle. The membrana granulosa of control follicles consisted of a single layer of squamous, darkly staining granulosa cells. After FSH treatment, nonstigmal granulosa cells separated slightly, and their nuclei became more clear and assumed an oval shape; in the stigma, these cells became widely separated, with round, light-staining nuclei containing one or two prominent nucleoli. The nonstigmal theca of FSH-treated follicles was similar to that of control follicles except that collagen fibers were more dissociated. In the stigma, collagen fibers were widely dissociated, and the theca swelled, presumably due to accumulation of extracellular fluid. Abundant fluid accumulated in the stigma, especially between the granulosa cells and their basement membrane and between the tunica albuginea and the theca externa. These changes in the lizard stigma are similar to those reported in mammals except that no marked inflammatory response occurs in the lizard stigma. We hypothesize that the Anolis follicle undergoes preovulatory luteinization, and that the stigma exhibits ischemic necrosis before rupture.

Animals↗
PubMed1985

Histological measurement of fat content of liver of dairy cows.

A total of 275 liver biopsies were performed on dairy cows in 6 Friesian and one Guernsey herd during the first 2 weeks after calving. Liver samples were processed by 2 independent histological procedures: (a) formalin-fixed frozen sections were stained with oil-red O (ORO), or (b) samples fixed in glutaraldehyde-osmium tetroxide were embedded in plastic and sections stained with toluidine blue (TOLB). The sections were then subjected to stereological point-counting procedures to assess the quantities of stainable fat present within the liver cells. Estimates of liver cell fat by the 2 techniques were highly correlated, although those obtained by the TOLB method were consistently lower than those obtained by the ORO method. The analytical sampling error was slightly lower in the TOLB method. The simpler ORO method should prove an acceptable alternative in the routine histology laboratory to the tedious and technically demanding TOLB method.

Adipose Tissue↗
PubMed1991

Morphometric mapping of regional myocyte diameters after healing of myocardial infarction in cats.

Myocyte diameters were measured in two models of healed myocardial infarction to test the hypothesis that myocyte hypertrophy is a function of proximity to the infarct. Left ventricular transmural and non-transmural myocardial infarctions were produced in cats by multiple ligatures of the distal tributaries of the left coronary artery system. Thirteen to twenty months after surgery the left ventricular free wall was cut longitudinally, embedded in plastic and stained for reticulum with modified silver stain. Myocardial cell diameters were measured from apex to base through the infarct. No regional differences were found in non-operated control hearts. In the transmural infarct hearts, all cell diameters were significantly increased in comparison to controls (P less than or equal to 0.05). In the hearts with non-transmural infarcts, cell diameters were significantly increased in tissues adjacent to the infarct, but as distance from the infarct increased the cell diameters were not different from controls. Cells from the transmural infarctions had a greater percent increase in diameter, compared to controls, than did cells from the non-transmural infarctions. There is a gradient increase in myocyte diameters in transmural and non-transmural healed myocardial infarctions; this increase is greatest in the tissues adjacent to the infarct. We conclude that cells close to a healed myocardial infarction hypertrophy because they are contracting against a non-compliant scar.

Animals↗
PubMed1985

Marginal opening of single and twin platinum foil-bonded aluminous porcelain crowns.

The marginal openings of single and twin foil-bonded aluminous porcelain crowns were compared in crowns fabricated indirectly for extracted teeth and directly on typodont teeth. The crowns were cemented with zinc phosphate, embedded in plastic, and sectioned. Marginal opening was measured directly with a traveling microscope. There was no significant difference between the marginal openings of twin- and single-foil crowns fabricated indirectly for extracted teeth. When the crowns were constructed directly on typodont teeth to eliminate the variables of impression-making and die fabrication, the single-foil crowns possessed a significantly smaller marginal opening than the twin-foil crowns. Both the twin- and single-foil complete porcelain crowns resulted in clinically acceptable margins. The single-foil crowns were easier to make.

Aluminum Oxide↗
PubMed1979

Analgesia for operative dentistry: a comparison of acupuncture and placebo.

Fifty-one volunteer patients participated in a study to evaluate the effectiveness of acupuncture as an analgesic for operative dentistry. For the twenty-six patients randomly assigned to an acupuncture group, needles were inserted through specially designed holders into the Ho-Ku points, located between the first and second metacarpals. An acupuncture pulse generator provided electrical current. For the twenty-five patients in a placebo group, the identical needle and holder arrangement was used. When inserted, however, the needles became embedded in plastic on the undersurface of the holders and did not touch the skin of the patient or receive any electrical stimulation. The patients and dentists were blind to this procedural variation. Analysis of ratings and responses indicated no differences in findings for the acupuncture and placebo procedures, with both having 100% success and high levels of patient acceptance. Since there was no electric current or penetration of the skin in the placebo group, the findings suggest that the successful use of acupuncture for restorative dentistry may be due to psychological and/or placebo effects in combination with a possible diminished need for analgesia because of the modern use of the high-speed drill.

Acupuncture Therapy↗
PubMed1980

Access of horseradish peroxidase (HRP) to the extracellular spaces of the maturation zone of the rat incisor enamel organ.

Adult rats received a single dose of HRP intravenously and were killed from 10 min to 6 hr after injection. Following fixation with glutaraldehyde, the enamel organs were treated with a Graham-Karnovsky-type procedure for peroxidase activity, post-osmicated, and embedded in plastic. Sections were studied with light and electron microscopes. Ten minutes after injection, reaction product was found in all extracellular spaces of the enamel organ, at the enamel-ameloblast interface over smooth-ended and intermediate ameloblasts, and in apical surface invaginations and vesicles of the latter cell types. The enamel-ameloblast interface over the ruffle-ended aemloblasts and the extracellular spaces within the ruffled border were free of reaction product and remained so for up to 6 hr. The apical terminal bars of the ruffle-ended ameloblasts functioned as a barrier to HRP. The basal terminal bars of the smooth-ended ameloblasts likewise seemed to prevent the passage of the HRP. Possibly, HRP flows in a lateral direction from groups of ruffle-ended into groups of smooth-ended ameloblasts. Between 10 min and 6 hr, HRP was cleared more rapidly from the extracellular spaces of the papillary layer than from those of the ameloblast layer, and there was little backflow of tracer from the ameloblast into the papillary layer. Eventually, tracer was cleared also from the extracellular spaces of the ameloblast layer, probably mainly through micropinocytosis by the ameloblasts. A working model is proposed regarding the handling of large molecules by the enamel organ in the maturation zone.

Ameloblasts↗
PubMed1990

Intestinal microsporidiosis as a cause of diarrhea in human immunodeficiency virus-infected patients: a report of 20 cases.

Chronic diarrhea accompanied by weight loss is a common and often debilitating problem associated with human immunodeficiency virus (HIV) infection. Enterocytozoon bieneusi, a newly identified species of the phylum of protozoa, Microspora, has been reported associated with chronic diarrhea and wasting in 11 acquired immunodeficiency syndrome (AIDS) patients in the United States, Europe, and Africa. Diagnosis has been based solely on the ultrastructural identification of this small, intracellular parasite in bowel biopsies. Seventy-one small bowel biopsies from 67 homosexual AIDS and AIDS-related complex patients with chronic diarrhea and with no pathogens identified by light microscopy on paraffin sections, were embedded in plastic and studied by light and transmission electron microscopy. Enterocytozoon bieneusi microsporidiosis was diagnosed by electron microscopy in 20 (22 biopsies) of the patients. More jejunal biopsies (16 of 36) were positive than duodenal biopsies (six of 35). Parasites and spores were clearly visible at the light microscopic level in the semi-thin plastic sections from 17 and 21 of the biopsies, respectively. In retrospect, parasites could be identified by light microscopy in standard hematoxylin and eosin-stained paraffin sections. Infection was confined to enterocytes covering the villi, especially the tips, and was associated with villous atrophy and cell degeneration, necrosis, and sloughing. Release of spores into the bowel lumen was evident. Colorectal biopsies from two of the patients with small bowel microsporidiosis were negative for microsporidia. Enterocytozoon bieneusi infection of the small bowel may be an important cause of diarrhea in HIV-infected persons.

Acquired Immunodeficiency Syndrome↗