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PubMed2006

Intracellular papillae of Actinocephalus (Eriocaulaceae-Poales) roots and their interaction with fungi: a light and transmission electron microscopy study.

The genus Actinocephalus comprises 25 species and is restricted to Brazil, occurring mainly in the Espinhaço Mountains of Minas Gerais and Bahia States. Previous anatomical studies have reported the occurrence of intracellular papillae in the Actinocephalus roots, without dealing with their ultrastructure and function. The purpose of this paper is to investigate the structure, the composition and the probable function of the intracellular papillae of Actinocephalus roots, based on light microscopy, transmission electron microscopy and histochemical tests. The intracellular papillae occurred in all root tissues, from the rhizodermis to the vascular cylinder; they presented different forms and sizes and, ultrastructurally, they corresponded to material deposited between the cell wall and the plasma membrane. The histochemical tests carried out were positive for cellulose, pectin and callose. The intracellular papillae are responses of the plant cells to the interaction with fungi. They work as a physical barrier restricting fungal penetration, and they may also favor the supply of water and nutrients to the plant, since they increase root absorption surface. This might explain why the species of Actinocephalus are among the tallest Eriocaulaceae despite their reduced radicular system and the nutritional deficiency of the soil in which they grow.

Eriocaulaceae↗
PubMed1998

Short unligated sticky ends enable the observation of circularised DNA by atomic force and electron microscopies.

A comparative study of the stabilisation of DNA sticky ends by divalent cations was carried out by atomic force microscopy (AFM), electron microscopy and agarose gel electrophoresis. At room temperature, molecules bearing such extremities are immediately oligomerised or circularised by addition of Mg2+or Ca2+. This phenomenon, more clearly detected by AFM, requires the presence of uranyl salt, which stabilises the structures induced by Mg2+or Ca2+. DNA fragments were obtained by restriction enzymes producing sticky ends of 2 or 4 nucleotides (nt) in length with different guanine plus cytosine (GC) contents. The stability of the pairing is high when ends of 4 nt display a 100% GC-content. In that case, 95% of DNA fragments are maintained circular by the divalent cations, although 2 nt GC-sticky ends are sufficient for a stable pairing. DNA fragments with one blunt end and the other sticky appear as dimers in the presence of Mg2+. Dimerisation was analysed by varying the lengths and concentrations of DNA fragments, the base composition of the sticky ends, and also the temperature. Our observation provides a new powerful tool for construction of inverted dimers, and circularisation, ligation analysis or short bases sequence interaction studies.

Cations, Divalent↗
PubMed1990

Cytomegalovirus in a macerated second trimester fetus: persistent viral inclusions on light and electron microscopy.

The macerated stillborn fetus represents at least one third of all perinatal deaths. Microscopic examination of these specimens is often unrewarding. We have reported a clinically unsuspected cytomegalovirus infection in a second trimester macerated fetus. Cells suggestive of CMV inclusions were identified by light microscopy, but electron microscopy confirmed the presence of viral infection and proved valuable in making the diagnosis even though necrosis was severe.

Abortion, Spontaneous↗
PubMed1986

Giant vascular eccrine spiradenomas: a report of two cases with histology, immunohistology and electron microscopy.

Two examples of a variant of benign spiradenoma are reported, both characterized by their large size and high degree of vascularity. The results of studies using light microscopy, transmission electron microscopy and immunohistology are described. The relationship of this unusual variant to other spiradenomas and their eccrine sweat gland origin is discussed. The possible misdiagnosis of this rare type of spiradenoma is emphasized.

Adenoma, Sweat Gland↗
PubMed1996

Deformed spinal needle tips and associated dural perforations examined by scanning electron microscopy.

BACKGROUND: The tips of modern thin Quincke-type spinal needles may be easily damaged by bone contact during the puncture. The purpose of this study was to find out the frequency of tip deformation in routine clinical work and the appearance of the dural perforations made by such damaged needles. METHODS: Two hundred and ninety-five Quincke-type needles (22G-29G) used in routine spinal anaesthesia were inspected by light microscopy. Scanning electron micrographs were taken of some of the damaged tips and of experimental dural perforations made by these. RESULTS: Four per cent of the needle tips were clearly bent or hooked and 11% were slightly bent. When an introducer needle was used (19 cases), one needle was clearly bent and one slightly bent. A puncture with a bone contact was associated with clear tip damage in 7%; a puncture without bone contact resulted in an undamaged or slightly bent needle tip in 99% of the cases. The numbers of bent tips among the various sizes were: 22G-2/21, 25G-13/40, 27G-28/231, 29G-1/3. In scanning electron microscopy (SEM) images of four clearly bent needle tips the deviation of the tip was between 10 microns and 20 microns. In SEM of eleven dural perforations, the holes made by needles with clearly bent tips were almost closed and three of them exhibited an "open tin can" appearance. None of the dural perforations was badly torn. CONCLUSIONS: We verified that the tips of modern thin spinal needles are vulnerable to damage due to contact with bone. However, the holes made in dura by needles with bent tips do not appear to be excessively torn.

Adolescent↗
PubMed1989

Blood-brain barrier disruption using mannitol: time course and electron microscopy studies.

Blood-brain barrier disruption with a hyperosmolar agent, mannitol, has previously been demonstrated to increase intracerebral methotrexate levels in rats. To determine the optimum conditions for blood-brain barrier disruption without producing neurological sequelae, adult Sprague-Dawley rats were infused with mannitol via the internal carotid artery at rates varying from 0.25 to 0.5 ml.s-1.kg-1. Methotrexate and Evans blue were used as markers of blood-brain barrier disruption. The optimum rate of mannitol that produced blood-brain barrier disruption without neurological sequelae was 0.25 ml.s-1.kg-1 for 20 s. The duration of blood-brain barrier opening was maximal for approximately 5 min and then rapidly reversed. Methotrexate levels on the mannitol-infused side were four to five times that of the noninfused hemisphere. Light microscopy and electron microscopy did not demonstrate any consistent changes that could be attributed to blood-brain barrier disruption nor did it elucidate the mechanism. This model should prove useful in the investigation of the treatment of intracerebral tumors with blood-brain barrier disruption. This study shows that maximal intracerebral methotrexate levels were obtained when methotrexate was infused before or within 5 min of the mannitol infusion.

Animals↗
PubMed1987

Dense HRP filling in pre-fixed brain tissue for light and electron microscopy.

The use of neuroanatomical markers in tissues that have been pre-fixed has been virtually ignored, even though this approach could offer certain advantages over in vivo methods, in terms of convenience of application and choice of markers. We have found that HRP can be used on well-fixed brains of cats and goldfish to fill neurons, dendrites, axons, terminals, glial cells, and glial processes for high-resolution light microscopy and electron microscopy. Best results were obtained using brains that were perfusion-fixed with 2.5% depolymerized paraformaldehyde and 1.5% glutaraldehyde. Two methods of HRP application were used: optically guided injections of microliter quantities into various regions of cat brain, and optic nerve fills in goldfish by attaching an HRP-filled polyethylene tube for periods of 1 day to 2 weeks. HRP applied in these ways to pre-fixed tissue was found to fill neurons or glial cells with solid label in the anterograde and retrograde directions.

Animals↗
PubMed1991

The epithelium of the rabbit vagina: a microtopographical study by light, transmission and scanning electron microscopy.

In order to obtain a more precise microtopographical surface map of the epithelium of the rabbit vaginal mucosa, investigations by light microscopy (LM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) have been systematically correlated. The epithelium was examined from the "portio vaginalis cervicis uteri" down to the "vestibulum". This study shows that the upper 2/3 of the vagina--which, in this species, is very long, measuring 13-14 cm--is lined by a single epithelial layer of tall ciliated and microvillous cells closely resembling the endocervical epithelium with which it is continuous. Moreover, these ciliated and microvillous cells also cover mucosal infoldings in the upper part of the vagina, especially those on the ectocervix and in the fornices, and scattered vaginal crypts. In particular, the ciliated elements decrease in number below the fornices, so that in large areas of the middle part of the vagina only microvillous cells are recognizable. Prior to the squamo-columnar junction, however, the ciliated cells increase again. This study also reveals that in the rabbit the squamo-columnar junction is located at the level of the pubic symphysis and that a squamous pluristratified epithelium covers only the lower 1/3 of the inner surface of the vaginal wall. In the estrous, i.e., precoital rabbit, the microvillous cells show little sign of secretion, whereas after mating they exhibit remarkable secretory features. These seem to increase progressively with postcoital stages (5 h, 24 h and 10 days) in the form of extensive mucification. These secretions often come in contact with spermatozoa retained in the mucosal infoldings and crypts, and are similar to those occurring in the endometrium, where they clearly depend upon progesterone activity. These epithelial features, different from those of other mammals, including humans, suggest that the greater part of the rabbit vagina accomplishes functions other than serving for copulation and as a fetal passageway. The present findings support the view that the rabbit vagina also plays a role as a reservoir of spermatozoa and in maintaining their viability, like the endometrium and endocervix.

Animals↗
PubMed1999

Long-term microstructural analyses of hydroxyapatite implanted in rats using laser-Raman spectrometry and scanning electron microscopy.

To investigate the long-term surface microstructure of a synthetic auditory ossicle (Apaceram) composed of dense hydroxyapatite (HA), thin HA disks were implanted subcutaneously into the interscapular regions of 12 rats. After 6, 14 and 20 months, implanted HA surfaces were observed using stereoscopic microscopy, scanning electron microscopy (SEM) and laser-Raman spectrometry. Visual observation by SEM at 6 months and by stereoscopic microscopy at 14 months indicated a progressive degradation of the HA disk surfaces implanted in the subcutaneous tissue. Visual observation by SEM at 14 and 20 months and by stereoscopic microscopy at 20 months indicated a progressive redeposition on the surfaces of the implants. Raman spectra compared half-peak breadths of v1 signal (PO4(3-), 960 cm(-1)) on the gray and white surface areas of implanted HA disks observed by stereoscopic microscopy. Analysis demonstrates that demineralization at 14 months and remineralization at 20 months occur on the gray areas; demineralization at 6 months and remineralization at 14 months occur on the white areas.

Animals↗
PubMed1985

Atherosclerosis of the microcirculation in the femoral head: based on a study by optical and electron microscopy of femoral heads removed at operation.

The authors studied 56 femoral heads removed at operation, using dissection stereoscopic microscopy and electron microscopy. They were able to demonstrate atherosclerotic lesions involving the microcirculation in the femoral head. Atheromatous changes in the external iliac and profunda femoris arteries have already been documented, but similar changes in the small vessels within the femoral head have not previously been noted in the literature.

Adult↗
PubMed1979

Comparative scanning and transmission electron microscopy of the prostatic gland in different species (mouse, rat, dog, man).

Man, dog, rat and mouse prostatic glandular cells were compared by light microscopy (LM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). In rodents and dogs, a merocrine secretion exists, and in these species the undulating surface represented a confluence of secretory granules. The prominent secretory blebs observed in dog and human benign prostatic hyperplasia (BPH) corresponded to apocrine secretions. Also variations in the amount of secretory activity were seen. Androgenic hormones were responsible for the differentiation of the prostatic epithelial cells during development. Therefore, an absence of microvilli as well as the appearance of ruffles, microplicae, and bare cells were seen in the prepuberal and castrated rat. In the elderly rat and in human BPH, a pleomorphism of the apical cell surface was evident.

Age Factors↗
PubMed1975

Scanning electron microscopy of the wall of the third ventricle of the brain of Rana temporaria. III. Electron microscopy of the ventricular surface of the median eminence.

From combined scanning and transmission electron microscopic studies it is concluded (1) that all surface specializations of the median eminence of Rana temporaria are protrusions of ependymal cells; (2) that the microvillus-like structures of the median eminence are transient differentiations of the ependymal cell surface, associated with the activity of the ependymal cells.

Animals↗
PubMed2000

The role of electron microscopy in gynecological pathology.

Electron microscopy, as a diagnostic method, has been available to pathologists for about half a century. Its use in studying normal and abnormal gynecological tissues has been applied during the second half of that period, and many works on specific female genital topics have been published. Several of those subjects are worthy of citing in a review of the present type. Clear cell carcinoma has been revealed to be a mullerian, rather than a wolffian, derivative. Small cell carcinoma of the ovary with hypercalcemia is comprised of cells shown ultrastructurally to be epithelial, but unlike surface epithelial cells, germ cells, sex-cord cells, or neuroendocrine cells. Further electron microscopic studies provided evidence that these small cell tumors are not adult diffuse granulosa cell tumors, endometrioid stromal tumors, primitive neuroectodermal tumors, or numerous other primary and metastatic small cell tumors. Electron microscopy has also been useful in determining that not all signet-ring cell tumors of the ovary are stromal, and that there are multiple types of signet-ring (vacuolated) cells in ovarian tumors. Smooth muscle tumors are well known to have multiple light microscopic phenotypes, and electron microscopy has proven to be diagnostic in many of these cases, especially in epithelioid smooth muscle tumors. A number of other gynecological neoplasms that have been better defined by electron microscopic studies are described. Embryology and histogenesis are other areas of study in which electron microscopy has been a major contributor of new information at the subcellular level. Electron microscopy, solely or in harmony with clinical information, light microscopy, and immunohistochemistry, has been and is a valuable tool for the pathologist in the study of histogenesis and accurate diagnosis of gynecological lesions.

Adenocarcinoma, Clear Cell↗
PubMed1984

Pineocytoma. Observation of an autopsy case by electron microscopy and cell markers.

An autopsy case of a 69-year-old female with pineocytoma was reported. The tumor showed neuronal differentiations, which were confirmed not only by light microscopy and electron microscopy, but also by a cell marker of neuron-specific enolase. In addition, existence of astrocytes in the tumor which distributed sparsely was ascertained by electron microscopy and cell markers such as S-100 protein and glial fibrillary acidic protein.

Aged↗
PubMed1975

Red cell surface structure. Stabilization by cholesterol sulfate as evidenced by scanning electron microscopy.

Scanning electron microscopic studies demonstrate that the normal biconcave shape of the human erythrocyte is maintained in hypotonic saline when physiological levels (10 minus 5M) of cholesterol sulfate are added to the solutions. Cholesterol sulfate is a naturally occurring sterol conjugate in plasma and erythrocyte membranes and we propose that it may belong to that class of amphipathic molecules responsible for the maintenance of structure of the erythrocyte by interaction with membrane components.

Cell Membrane↗