Ultrastructural findings after microsurgical interventions on the carotid artery of the rat

For 10 years, it has been known that operations on vessels 1 mm in diameter are possible. The application of microvascular techniques to neurosurgery demands microscopic and ultrastructural examinations of the effects of such interventions on small vessels. Histological examinations can help to provide answers to questions concerning operating technique, ultrastructural examinations give information on the indications for operation. Since these questions have not been studied previously, preliminary examinations on easily accessible vessels are necessary. For this purpose, the common carotid artery of the rat was chosen. Histological and ultrastructural examinations were carried out on end-to-end anastomoses of these vessels. The ultrastructural findings are described and compared with anatomical findings in normal and abnormal vessels in the rat.     

Ultrastructural and morphometric features of the acetylcholine innervation in adult rat parietal cortex: an electron microscopic study in serial sections

This study was aimed at characterizing the ultrastructural morphology of the normal acetylcholine (ACh) innervation in adult rat parietal cortex. After immunostaining with a monoclonal antibody against purified rat brain choline acetyltransferase (ChAT), more than 100 immunoreactive axonal varicosities (terminals) from each layer of the Par 1 area were photographed and examined in serial thin sections across their entire volume. These varicosities were relatively small, averaging 0.6 micron in diameter, 1.6 microns 2 in surface, and 0.12 micron 3 in volume. In every layer, a relatively low proportion exhibited a synaptic membrane differentiation (10% in layer I, 14% in II-III, 11% in IV, 21% in V, 14% in VI), for a I-VI average of 14%. These synaptic junctions were usually single, symmetrical (> 99%), and occupied a small portion of the surface of varicosities (< 3%). A majority were found on dendritic branches (76%), some on spines (24%), and none on cell bodies. On the whole, the ACh junctional varicosities were significantly larger than their nonjunctional counterparts, and both synaptic and nonsynaptic varicosities could be observed on the same fiber. A subsample of randomized single thin sections from these whole varicosities yielded similar values for size and synaptic frequency as the result of a stereological extrapolation. Also analyzed in single sections, the microenvironment of the ChAT-immunostained varicosities appeared markedly different from that of unlabeled varicosity profiles randomly selected from their vicinity, mainly due to a lower incidence of synaptically targeted dendritic spines. Thus, the normal ACh innervation of adult rat parietal cortex is predominantly nonjunctional (> 85% of its varicosities), and the composition of the microenvironment of its varicosities suggests some randomness in their distribution at the microscopic level. It is unlikely that these ultrastructural characteristics are exclusive to the parietal region. Among other functional implications, they suggest that this system depends predominantly on volume transmission to exert its modulatory effects on cortical activity.     

Ultrastructural study of the A-W GC-bone interface after long-term implantation in rat and human bone

The interface between apatite- and wollastonite-containing glass-ceramic (A-W GC) and bone after long-term implantation was studied by scanning and transmission electron microscopy (SEM and TEM) using rat and human specimens. First, particles of A-W GC (100-220 microns in diameter) were implanted into rat tibiae, and specimens were prepared for observation at 24, 48, 72, and 96 weeks after the operation. These long-term specimens showed an A-W GC-bone interface different from that at an earlier stage, which was investigated in our previous studies. SEM showed that the Ca-P-rich layer was wider, suggesting that leaching of ions from the A-W GC had continued even after bonding with bone. In some regions, the material particles were evidently replaced by the bone. TEM showed that the intervening apatite layer had become indistinct, and that A-W GC had intermingled with bone at the interface. In some regions, the surface of the A-W GC was degraded. These findings suggest that the surface region of A-W GC is slowly replaced by bone. Second, a human bone specimen, which included A-W GC particles (300-700 microns in diameter) implanted as a bone filler for about 75 weeks was harvested and investigated. Excellent A-W GC-bone bonding was observed, and the ultrastructure of the interface was similar to that in rats after long-term implantation. This finding demonstrated that A-W GC possibly worked in human bone in the same way as in rat bone, showing excellent bioactivity.     

Ultrastructural study of binucleation in cells of the rat adrenal glomerular zone after a prolonged low-sodium diet

Binucleate cells have been found in the glomerular zone of the adrenal cortex in rats subjected to low-sodium diets. By considering the various possibilities for their production, both the findings of nuclei in process of constriction and nuclei identical in form, confronted and smaller in size than those of neighbour cells, are in agreement with an amitotic nuclear division as the possible mechanism for the formation of these cells.     

Ultrastructural changes in the rat neurohypophysis after a prolonged protein-free diet

The effects on gallbladder contraction of three structurally related peptides, secretin, glucagon and the vasoactive intestinal peptide (VIP) have been compared in urethane-anesthetized guinea pigs. Secretin and glucagon had no effect alone but augmented cholecystokinin (CCK)-induced contractions. VIP decreased CCK-induced contractions.     

Malacoplakia of the prostate and seminal vesicle. Ultrastructural study and review of the literature

OBJECTIVES: The present study describes a case of malacoplakia of the genitourinary tract arising in the seminal vesicle and prostate and reviews similar cases previously reported in the literature. METHOD: A 67-year-old male consulted for hemospermia and voiding symptoms. Prostatic neoplasm was suspected on the basis of the clinical and radiological findings. RESULTS: The diagnosis was made only after biopsy and histological analysis. Electron microscopy is a very useful tool. Long-term antibiotic therapy may achieve optimal results. Treatment with fluoroquinolones was successful. CONCLUSION: To avoid unwarranted radical approaches, we underscore the possibility that prostatic pseudotumors may be misinterpreted as neoplasia. Malacoplakia is diagnosed only by histology and requires medical treatment.     

Circannual morphometric investigations of the rat suprachiasmatic nucleus after pinealectomy, ganglionectomy and thyroidectomy

With the advent of combinatorial chemistry a new paradigm is evolving in the field of drug discovery. The approach is based on an integration of chemistry, high-throughput screening and automation engineering. The chemistry arm is usually based on solid-phase synthesis technology as the preferred approach to library construction. One of the most powerful of the solid-phase methods is encoded split synthesis, in which the reaction history experience by each polymeric bead is unambiguously recorded. This split-and-pool approach, employing chemically robust tags, was used to construct a 85,000-membered dihydrobenzopyran library.     

Ultrastructural alterations of the cortical epithelial cells of the rat thymus after cyclophosphamide treatment

A single dose of cyclophosphamide (CY) was administered to Sprague-Dawley rats to investigate the effects of CY on thymic cortical epithelial cells (TCE) at the ultrastructural level. The most striking finding among the alterations in the TCE after CY treatment was a cytoplasmic vacuolization with an increased amount of granular and membranous content. The granular content appeared not only as dense bodies but also as loosely aggregated forms or finely dispersed granules. The membranous structures appeared in various forms including vesicular, tubular, vacuolar and irregular membranous structures and myelin figures. Some of the membranous structures contained granular material. Several vacuoles were closely associated with the endoplasmic reticulum (ER). The morphological alterations of the ER were also remarkable. The Golgi apparatus, mitochondria and vesicles increased in number. The cytoplasm became densely granulated due to an increased number of ribosomes and an increased amount of granular material. The tonofilaments lost their original array and increased in amount. The cell surface exhibited many cytoplasmic processes like microvilli. It seems that the above features result not only from some damage by CY, but also signs of a hyperfunctional state of the TCE, probably due to their important functions in repopulation and maturation of the cortical thymocytes during recovery after CY-induced acute thymic involution, including the secretion of some humoral factors.     

Changes in muscularis externa of rat small intestine after myenteric ablation with benzalkonium chloride: electron microscopic and morphometric study

The influence of the intrinsic innervation on the muscularis externa of the rat small intestine was studied by chemical ablation of the myenteric plexus with benzalkonium chloride (BAC). The resulting severe hypertrophy (cell hypertrophy of 96-133% and hyperplasia) differs from working hypertrophy by the distribution and degree of muscle thickening and by characteristics of the extracellular matrix: narrowing of muscle interspaces of 43%; lack of increased collagen; changes in the ratio of interstitial cells of Cajal (ICCs) to fibroblasts from 1.6:1 to 0.8:1 with no numerical decrease in either type of cell; decreased interconnections of ICCs to muscles and nerves due to deformed ICCs; a 197% increase in vascularization (capillaries, venules) and lymphatics in both muscle layers and in the myenteric plexus cleft, possibly initiated by release of fibroblast growth factor from myelin fragmentation after nerve damage; and increased macrophages, plasma cells, monocytes and mast cells in the myenteric plexus cleft. These all signify the neural influence on the morphodifferentiation of the muscularis externa in concert with the extracellular matrix components.     

A morphological and morphometric study of the testicle in the rat vasectomized by electrocautery technics]

Symmetry of posterior intrasylvian cortices (e.g., planum temporale, planum parietale) has been suggested to represent a risk factor for developmental disorders of language and reading. Using high-resolution magnetic resonance morphometry, we studied 21 right-handed children with developmental language disorder of the phonologic-syntactic type, and found normal left-right asymmetry of the planum temporale and planum parietale when compared with 21 matched controls. The planum temporale was bilaterally smaller in the affected children, a finding accounted for by their approximately 7% smaller forebrain size. Our data do not support a role of gross visible unilateral or bilateral abnormalities of posterior intrasylvian ontogenesis in this disorder.     

Freeze-fracture study of rat ventral prostate: the columnar epithelial cell

The organization of the secretory epithelium of the rat ventral prostate as seen by freeze-fracture is analyzed. Ultrastructural interpretation of the tall columnar epithelial cell is facilitated by the axial regionalization of the cytoplasm. The endoplasmic reticulum, which exists in all the regions of the cell, appears to have a role in the maintenance of cellular organization. Its cisternae delimit the spaces for the nucleus, the Golgi, and the apical secretory apparatus. Elements involved in the formation of secretory products for export are located within the apical region of the cell and are regionally separated from the Golgi complex. Structural and functional specializations of the plasma membrane in the apical, lateral, and basal areas are illustrated. Artifacts related to specimen preparation procedures are reported. Displacement of membrane particles, which we observed in the fracture faces of plasma and intracellular membranes, appears related to fixation at low temperature. Fixation at 37 degrees C, which does not induce membrane-particle displacement, results in proliferation of tight-junctional elements.     

Sympathetic neurotransmission in isolated rat atria after sensory-motor denervation by neonatal treatment with capsaicin

Long-term interactions between sympathetic and sensory-motor nerves have been shown in several tissues. Previous investigations in this laboratory have demonstrated an increase in cardiac sensory-motor innervation after neonatal sympathectomy by guanethidine and an increase of perivascular sympathetic neurotransmission after neonatal treatment by capsaicin. The present study evaluated the effects of sensory-motor denervation on sympathetic neurotransmission in the heart. Newborn rats were injected with capsaicin or its vehicle (Tween 80). Sympathetic neurotransmission was studied in isolated atria driven at a constant rate (4 Hz) by measuring cardiac responses to electrical field stimulation, in the presence of atropine 1 microM. Inotropism of tyramine, norepinephrine and calcitonin gene-related peptide was also tested. Neonatal capsaicin treatment did not affect cardiac responses to trains of an increasing number (2-32) of field pulses. Moreover, inotropic responses to tyramine did not differ between control, capsaicin- and Tween 80-treated preparations. Neither maximal effect nor pD2 values were significantly different between the groups. Similarly, the inotropism of calcitonin gene-related peptide was comparable in all groups of atrial preparations. In marked contrast to earlier papers on blood vessels, this study shows a lack of effect of sensory-motor denervation by neonatal capsaicin treatment on cardiac sympathetic neurotransmission. The different neuronal plasticity of vascular and cardiac sensory innervation will be discussed. The present results also indicate that capsaicin-induced sensory-motor denervation is not associated with changes in cardiac responsiveness to calcitonin gene-related peptide.     

Mucous cell metaplasia in rat nasal epithelium after a 20-month exposure to ozone: a morphometric study of epithelial differentiation

The present study was designed to examine the effects of long-term ozone exposure on nasal epithelia and intraepithelial mucosubstances (IM) throughout the nasal airways of F344/N rats. Animals were exposed to 0 (controls), 0.12, 0.5, or 1.0 ppm ozone, 6 h/day, 5 days/wk, for 20 mo. Rats were killed 1 wk after the end of the exposure, and nasal tissues were processed for light and electron microscopy. Standard morphometric techniques were used to determine epithelial cell densities and the amounts of IM in the surface epithelium lining the nasal airways. No mucous cells or IM were present in the epithelia lining the nasal lateral meatus and maxillary sinus of rats exposed to 0 or 0.12 ppm ozone. In contrast, rats exposed to 0.5 or 1.0 ppm ozone had marked mucous cell metaplasia (MCM) with numerous mucous cells and conspicuous amounts of IM in the surface epithelium lining these upper airways. Ozone-induced increases in total epithelial cells (i.e., epithelial hyperplasia) were present only in rats exposed to 1.0 ppm. The results of this study indicate that rats chronically exposed to 1.0 or 0.5 ppm, but not 0.12 ppm, ozone can develop marked MCM with significant increases in IM in both proximal and distal nasal airways. The epithelial changes observed throughout the nasal passages of ozone-exposed rats may be adaptive responses in an attempt to protect the upper and lower respiratory tract from further ozone-induced injury.     

Trigeminal denervation and operant behavior in the rat.

39 male Wistar rats underwent selective sectioning of trigeminal sensory and motor nerves in 2 experiments to examine the contribution of the sensorimotor system to the control of instrumental responses reinforced with food or water. It was hypothesized that trigeminal denervation would disrupt motivational systems mediating Ss' thirst and hunger. Results show that unilateral sectioning of either Section V sensory or V motor nerves had no significant effect on leverpressing. Bilateral sectioning significantly reduced leverpressing, and the deficit was greatest in Ss with trigeminal motor nerve sectioning. It is concluded that trigeminal orosensory or oromotor denervation disrupts performance on a food- or water-reinforced task in which execution does not require a trigeminally mediated response. Findings are discussed in terms of motivational and reinforcement accounts of instrumental learning. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Histopathological and morphometric study of the late effects of heavy-ion irradiation on the spinal cord of the rat

Recently, interest has focused on the human gene encoding the putative protein homologous to VAT-1, the major protein of the synaptic vesicles of the electric organ of the Pacific electric ray Torpedo californica, after it has been localized on chromosome locus 17q21 in a region encompassing the breast cancer gene BRCA1. Chromosomal instability in this region is implicated in inherited predisposition for breast and ovarian cancer. Here we describe isolation and biochemical characterization of a mammalian 48 kDa protein homologous to the VAT-1 protein of Torpedo californica. This VAT-1 homolog was isolated from a murine breast cancer cell line (Ehrlich ascites tumor) and identified by sequencing of cleavage peptides. The isolated VAT-1 homolog protein displays an ATPase activity and exists in two isoforms with isoelectric points of 5.7 and 5.8. cDNA was prepared from Ehrlich ascites tumor cells, and the murine VAT-1 homolog sequence was amplified by polymerase chain reaction and partially sequenced. The known part of the murine and the human translated sequences share 97% identity. By Northern blots, the size of the VAT-1 homolog mRNA in both murine and human (T47D) breast cancer cells was determined to be 2.8 kb. Based on the presented data, a modified gene structure of the human VAT-1 homolog with an extended exon 1 is proposed. VAT-1 and the mammalian VAT-1 homolog form a subgroup within the protein superfamily of medium-chain dehydrogenases/reductases.