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At least 1,369 records · Page 76Linked to original sources
PubMed1996

Fine structure of the pecten oculi of the barred owl (Strix varia).

The pecten oculi of the barred owl (Strix varia) has been examined by light and transmission electron microscopy. The pecten in this species is of the pleated type and is small in comparison to the size of the ocular globe. The pecten consists of 8-10 accordion-like folds that are linked apically by a pigmented tissue bridge. Each fold contains numerous capillaries, larger supply and drainage vessels, and abundant pleomorphic melanocytes. Most of these capillaries are extremely specialized vessels that possess plentiful microfolds on both the luminal and abluminal surfaces. Some capillaries however display only a few microfolds. The endothelial cell bodies are extremely attenuated, with most organelles located near the nucleus. All capillaries are surrounded by a very thick fibrillar basal lamina, which is thought to provide structural support to these small vessels. Pericytes are commonly found within these thickened basal laminae. Numerous melanocytes are also present, with processes that form an incomplete sheath around the capillaries. These processes are also presumed to provide structural support for the capillaries. As in other avian species, the morphology of the barred owl pecten is indicative of extensive involvement in substance transport. When compared to the pecten of more visually-oriented species, this pecten is smaller, has fewer folds, and displays a reduced number of microfolds within the capillaries. In these and other features, the barred owl pecten is similar to the pecten of the great horned owl (Bubo virginianus).

Animals↗
PubMed1996

Retinal photoreceptor fine structure in the Australian galah (Eolophus roseicapillus) (Aves).

The retinal photoreceptors of the galah (Eolophus roseicapillus), an Australian cockatoo, consist of rods, single cones and double (unequal) cones present in a ratio of about 1:3:3 respectively. The rods are long slim cells which are believed to undergo retinomotor movements. The rod inner segment displays an ellipsoid of mitochondria, much rough endoplasmic reticulum (RER), numerous polysomes and some autophagic vacuoles. No hyperboloid of glycogen was noted. Single cones show a slightly tapered outer segment, no oil droplet but a prominent ellipsoid at the apex and glycogen scattered throughout the inner segment. Double cones consist of a chief member which displays a heterogeneous oil droplet but no paraboloid of glycogen and an accessory cone with no oil droplet but a prominent paraboloid. All cones show below the ellipsoid plentiful polysomes, RER, Golgi zones and autophagic vacuoles. Cones are not felt to undergo retinomotor movements. In the light-adapted state the pigment-laden apical processes of the retinal epithelium (RPE) cells surround all photoreceptor types down to the inner segments. Along the length of the contiguous membranes between the two members of the double cones are membrane densifications that are presumed to be junctions. All cone photoreceptors are relatively small in diameter and hence closely packed. Rods and cones (both types) display both invaginated (ribbon) and superficial (conventional) synaptic sites.

Adaptation, Ocular↗
PubMed1996

Fine structure of the pecten oculi in the Australian galah (Eolophus roseicapillus) (Aves).

The pecten oculi of the Australian galah (Eolophus roseicapillus) has been examined by both light and electron microscopy. In this species the pecten is large relative to the size of the eye and is of the pleated type. It consists of 20-25 accordion folds that are joined apically by a bridge of tissue which holds the pecten in a fan-like shape widest at its base. Within each fold are many melanocytes, numerous capillaries as well as larger supply and drainage vessels. The capillaries are extremely specialized for transport functions and display extensive microfolds on both their luminal (inner) and abluminal (outer) borders. Except for the nuclear region which also contains most of the organelles, the endothelial cell bodies are extremely thin. These capillaries are surrounded by thick fibrillar basal laminae which are felt to be structurally important. Pericytes are a common feature within the basal lamina of capillaries. The numerous pleomorphic melanocytes which more or less surround the capillaries are also presumed to be important in structural support of the pecten. The pecten represents a supplementary retinal circulation and is comparable to the falciform process of some teleosts, the conus papillaris of reptiles, the supraretinal vessels of amphibians and some teleosts and the intraretinal vessels of mammals, all of which are felt to be alternative methods of bringing nutrients to the inner retina.

Adaptation, Ocular↗
PubMed1996

Influence of initial implant mobility on the integration of titanium implants. An experimental study in rabbits.

In the present study, the influence of initial instability on the healing of titanium implants was studied in 9 lop-eared rabbits. Titanium implants (Brånemark System) were inserted in the tibiae, a location with cortical bone only, in such a way that they were either stable (control), rotation-mobile, or totally mobile. Implants were also inserted in the distal femoral condyles, representing an implantation bed with mainly cancellous bone, so they either showed no initial mobility (control) or were rotation-mobile. After 12 weeks of healing, the implants were retrieved, together with surrounding bone, fixed, dehydrated, and embedded in plastic resin. About 10 micron thick ground sections were prepared for light microscopic morphometry. The mineralized bone to titanium contact, and the amount of bone occupying the threads, were calculated, whereafter the outcome of the different locations were compared. All retrieved implants were clinically stable at the of the experiment. For the tibia sites, a statistically significant less bone to titanium contact, and a less amount of bone in the threads, were found for the totally mobile implants, as compared to the corresponding initially stable controls. Moreover, a statistically significant higher amount of bone was found in the threads of the rotation-mobile implants inserted in the femoral condyle as compared to their initially stable controls. The study indicated that initial rotation-mobility, independent if it occurs in cortical or trabecular bone, does not necessarily lead to an inferior integration of unloaded implants. However, initial total implant mobility within the cortical layer results in a statistically significant less amount of bone around the implants, as compared to stable controls.

Animals↗
PubMed1996

Influence of soft tissue contamination on the integration of titanium implants. An experimental study in rabbits.

In the present study, the influence of peroperative soft tissue contamination on the healing of titanium implants was studied in 9 lop-eared rabbits. Titanium implants (Brånemark System) were inserted in the tibiae, a location with cortical bone only, in such a way that one group was inserted the standard way (control), and another group was contaminated for 30 s in the adjacent soft tissues, prior to insertion. The implants were allowed to heal for 12 weeks and were then retrieved together with surrounding bone, fixed, dehydrated and embedded in plastic resin. About 10 micron thick ground sections were prepared for light microscopic morphometry. The mineralized bone-to-titanium contact, and the amount of bone occupying the threads, were calculated for each implant, and the results of the two groups were compared. All retrieved implants were clinically stable at the end of the experiment. Regarding bone-to-titanium contact and bone area within the threads, a statistically nonsignificant difference was observed between the 2 groups. This study indicated that peroperative soft tissue contamination of c.p. titanium implants does not prevent osseointegration from occurring, when studied in the rabbit tibia.

Animals↗
PubMedDate not supplied

Spontaneous degeneration of testicular germ cells in congenitally athymic nude mice of four strains: a light microscopical observation.

Many hormonal studies have demonstrated that the presence of thymic factors affects testicular function. However, morphological studies on the testis in the absence of thymic factors are very limited. In the present study, seminiferous tubules of nude mice of four strains were light microscopically observed in order to investigate the effect of congenital athymia on germinal cell components. Testes obtained from congenitally athymic nude mice of CD1, BALB/c-nu/nu, LASAT, and KSN strains were fixed in Bouin's solution, dehydrated, and embedded in plastic. The samples were cut and their sections were stained with hematoxylin and eosin. The results showed that degeneration of testicular germ cells was focally observed in all four strains of athymic mice. The degenerating morphology was characterized by karyopyknosis and karyolysis of immature germ cells, multinuclear giant cell formation, and severe depletion of epithelial components with remaining Sertoli cells and/or some spermatogonia. KSN nude mice showed the most severe degenerative changes among the four strains of nude mice examined. Their significant degenerative changes first appeared at 2 weeks of age. In contrast, CD1 nude mice showed very slight degenerative features even at 20 weeks of age. BALB/c-nu/nu and LASAT nude mice had more degenerated epithelia than did CD1 nude mice; however, their significant degenerative changes were apparent at 20 but not at 10 weeks of age. Therefore, the severity and the onset of spontaneous degeneration and depletion of testicular germ cells in congenitally athymic mice were different among the four strains examined.

Animals↗
PubMed1998

Male reproductive toxicity of phosphamidon: histopathological changes in epididymis.

Phosphamidon, a neurotoxic insecticide, was tested for male reproductive toxicity with special reference to the epididymis. The insecticide was fed to Wistar strain male albino rat at 35 ppm concentration in drinking water ad libitum for 30 days. After vascular perfusion, thin slices of caput and cauda epididymidis were embedded in plastic, cut at 1 micron thickness and stained in toluidine blue for light microscopic observation. Principal cells of the caput epididymidis were vacuolarized and seen to pinch off fragments apically. In the proximal cauda the clear cells increased in height and in the size of the secondary lysosomal granules. In the distal cauda the clear cells appeared swollen out of proportion. Phosphamidon appears to affect the principal cells indirectly through its toxic effect on the Leydig cells; the clear cells of the cauda appear to be directly vulnerable to the toxic action of the pesticide.

Animals↗
PubMed1998

Effects of corticosteroids on epithelial structure and smooth muscle function of rat trachea.

Corticosteroids, efficient drugs for the treatment of severe asthma, may have numerous side effects. We investigated the effects of 7 days of treatment with triamcinolone (1.2 mg x kg(-1) x day(-1)) on the epithelial structure, tracheal smooth muscle cross-sectional area and contractility in the rat. The corticosteroid-injected rats were compared to pair-fed, and pair-weighed animals. Histological studies were performed on transverse sections of glutaraldehyde-fixed tracheal blocks embedded in plastic. In the preparations taken from corticosteroid-injected, pair-fed and pair-weighed animals, pharmacological stimulation with single (10(-3) M) or cumulative (10(-8)-10(-3) M) concentrations of carbachol (in corticosteroid-injected and pair-fed animals), either inside (In) or outside (Out) of the tracheal lumen, was performed and contractions of the tracheal smooth muscle were recorded. We found that triamcinolone administration: 1) reduced the number of epithelial cells and the tracheal smooth muscle cross-sectional area; 2) induced a decrease in maximal tension (Tmax (g); Out: 2.42+/-0.17, 1.03+/-0.1 in pair-fed and corticosteroid-injected, respectively; In: 2.55+/-0.16, 1.1+/-0.16, respectively) without affecting the sensitivity of the tracheal smooth muscle; and 3) reduced the time required to reach 50% Tmax in carbachol (In) preparations. We conclude that the observed changes resulted from atrophy of tracheal smooth muscle induced by undernutrition and atrophy of tracheal smooth muscle and tracheal epithelium induced by corticosteroid treatment.

Animals↗
PubMed1999

A modified staining method for connective tissue in semi-thin histological sections of peripheral and cranial nerves.

A simple staining method for collagen in semi-thin sections of nerves is described. This technique consists of applying basic fuchsin (0.05%) solution for 2 min. to +/- 1.25 microns plastic resin-embedded sections after routine toluidine blue staining. This staining method clearly demonstrates the amount and orientation of collagenous connective tissue in the nerve, both in transverse and longitudinal sections.

Animals↗
PubMed1998

Use of methacrylate De-embedding protocols for in situ hybridization on semithin plastic sections with multiple detection strategies.

New plastic resins are gradually replacing traditional paraffin-embedding in situ hybridization (ISH) strategies. One unique resin that has not been fully investigated or exploited with respect to light microscopic ISH is a methacrylate mixture. The advantage of this resin is its ability to be removed from tissues postsectioning, dramatically increasing hybridization signal compared to that obtained in other plastics. The goal of this study was to evaluate the general applicability of the methacrylate embedding acetone de-embedding (MEADE) technique for ISH investigations. Several high-resolution, high-sensitivity ISH protocols are described, using both end-labeled oligonucleotides and randomly primed DNA probes (200-400 BPS), signal amplification by catalyzed reporter deposition (CARD), and chromogenic and fluorescent detection methods. With slight modification, the MEADE ISH technique permitted localization of bacterial symbionts in fragile gill tissue and collagen transcripts in foot tissue of two marine bivalves. MEADE ISH has proved extremely versatile and will likely be suitable for many future applications.

Animals↗
PubMed1987

Is it necessary to embed bone marrow biopsies in plastic for haematological diagnosis?

With the increase in the use of bone marrow trephines for diagnosis have come numerous reports that traditional methods of preparation (by decalcification and embedding in paraffin wax) should be replaced by plastic embedding to avoid decalcification. It has been argued that only by this means can the high quality preparations needed for accurate haematopathological diagnosis be achieved. The present study challenges this viewpoint and argues that with a little extra care and attention conventional paraffin embedding techniques can give equally high quality preparations. Sections prepared in this way meet the diagnostic needs of the haematologist, without requiring a separate technique to be established in the pathology laboratory solely for bone marrow trephines.

Biopsy↗
PubMed1987

[Methods for long-term storage of anatomical demonstration objects].

2 methods for longterm conservation of anatomical objects have been described. The former concerns the use of methylmethacrylate (the plastic material) for embedding of anatomical objects into different forms. The 2nd method uses the same plastic material for impregnation of anatomical objects. The authentic anatomical models produced by the both methods possess very good demonstrative features. They are solid and cheap.

Methylmethacrylate↗
PubMed1988

Glycol methacrylate (GMA) embedding for light microscopy. II. Immunohistochemical analysis of semithin sections of undecalcified marrow cores.

A routine method allows bone marrow biopsy specimens to be embedded in glycol methacrylate (GMA), a water miscible plastic, and to benefit from the advantages of good morphology with immunoperoxidase detection of a wide range of cellular antigens useful in diagnosing and classifying various haematopoietic disorders. Marrow cores were fixed in cold Bouin's solution, rinsed in cold phosphate buffer, dehydrated in cold methanol, infiltrated and embedded in cold GMA, then polymerised at 4 degrees C. Sections were cut at 2 micron thickness with a Tungsten carbide knife in a Jung's high performance microtome (Autocut). Antigenecity was preserved when drying slides at room temperature but pronase digestion was necessary to re-expose the antigens in bone marrow biopsy sections embedded in GMA. Histostik, a new adhesive, was used to coat the glass slides to prevent section loss during enzyme digestion and immunostaining procedures. This method of adapting plastic embedding to undecalcified marrow cores preserves marrow architecture and cellular details and it can serve as a useful adjunct to analyse the bone marrow from patients with myeloproliferative and lymphoproliferative disorders. This technique may also be applicable in non-haematological malignant conditions which affect the marrow.

Antigens, Differentiation↗