The physiological necessity of the dual afferent blood supply of the liver and the morphological features of the macrocirculation are well understood. The microcirculation, however, still poses a number of unsolved questions. In particular the nature of the terminal junctions of the arterial and portal blood stream with the sinusoids has so far not been satisfactorily elucidated (1-2). Scanning electron microscopy alone or in combination with corrosion casts cannot solve the problem, because it remains difficult to tell the different vessels apart. Under favorable circumstances the terminal portal vein is the easiest to be distinguished with corrosion casts. This is due to the fact that its relatively wide branches surround the classical liver lobules along the major parts of their circumference. The diameter of the terminal hepatic artery is in its initial segments not as wide as the initial segments of the terminal portal vein.

The angioarchitecture of the hard palate mucosae of young rabbits was investigated by using microvascular casting of low density resin (Mercox®). The injected specimens were examined by scanning electron microscope (SEM). The palatine mucosa and the adjacent gingiva have an important function during the mastication, vocalization and swallowing. The purpose of this paper is to analyse the structure of the micro vasculature of the palatine mucosa.

The animals were anesthetized and perfused with approximately 500ml of prewarmed (37°C) heparinized saline. Then, 30-40ml of Mercox® CL2-B, prepared conforming the manufacterer's intructions, were carefully injected via aorta artery under manual pressure. After the complete resin polymerization, specimens were dissected and macerated with 10% NaOH for several days at room temperature. The vascular casts were rinsed in distelled water, dried, mounted in stubs, coated with gold and examined in JEOL 6100 scanning electron microscope.

In order to warrant the blood supply to the nervous system it is necessary an efficient and intact blood circulation system, where the pattern of vascularization is of fundamental importance. In this way, we intend to demonstrate the tridimensional architecture and the pattern of vascularization in the region of the brain cortex of frontal and parietal lobes. There for, our proposal is to study the microvascularization of the rabbit cortex (Oryctologus cuniculus).The studies about blood irrigation of the brain regions are very important to verify the capilar nets and their relations with intensity of blood flux in specified regions of central nervous system.

The articles about vascularization that uses models obtained by the injection of aloplastic materials whose viscosity is similar to the blood's that allows the difusion until the capilar net was introduced by Murakami (1971). Lametschwandter et al (1984), studied aspects of corrosion technique to microvascular models.

Vesicles derive their structure from the aqueous environment surrounding and within them. It follows that traditional EM specimen preparation techniques of fixation, dehydration and drying can induce a variety of morphological changes to the membranes. Vitrification of aqueous suspensions of vesicles provides a means for observation of these structures in their fully hydrated unfixed state. Common cryogenic techniques for the visualization of these and other colloidal particles include cryo-TEM of vitrified thin films and freeze-fracture TEM (FF-TEM) of platinum replicas. We report the use of cryo-high resolution SEM (cryo- HRSEM) and cryo-STEM for the study of the morphology of membrane features of synthetic extruded vesicles.

LUVs were prepared by the extrusion method. Dried lipid films of l-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) were hydrated with 0.5 mL of Milli-Q water and stirred for 10 minutes to make suspensions (10 mM in lipids) which were extruded 19 times through a polycarbonate filter with 100 nm pores.

Lipid vesicles are used as drug delivery vehicles for the slow sustained release of a drug compound to a specific site in the body. This translates to more efficient medication with limited side effects. Although unilamellar drug delivery vesicles have progressed greatly, they are still limited in there applications. Our group has designed a second generation drug release system, the “vesosome“ which incorporates an aggregate of lipid vesicles encapsulated in a second lipid membrane. The two separate membranes can be specialized to allow for increased drug encapsulation and better control over drug release rate, which leads to a more general drug delivery system.

Lipid vesicle aggregates were formed by using a ligand-receptor system (biotinated lipids protruding from the vesicle surface crosslinked with streptavidin). The streptavidin/biotin system is one of the strongest in nature, providing specific binding.

Recombinant DNA techniques were used to prepare a protein modeled after the consensus sequence of Nephila clavipesspider dragline silk, incorporating methionine residues to serve as redox “triggers”. In addition a water-soluble 27 residue peptide model of the dragline silk consensus amorphous sequence, representing a single amorphous block in the protein sequence, was prepared and characterized to gain additional insight into the behavior of the amorphous phase. X-ray diffraction, electron diffraction, transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR) were used to characterize the ability of the recombinant protein to form (β-sheet crystals and the effect of the oxidation state of the redox trigger on crystallinity and noncrystalline order in the sample. The formation of intractable β-sheet crystallites is a major cause of insolubility in proteins that can form this type of secondary structure. Changes in crystallinity were observed when triggered/reduced (insoluble) and untriggered/oxidized (soluble) protein samples were compared.

Fibrous proteins are molecules whose secondary structures are their dominant motifs due to their highly repetitive amino acid sequences. Most fibrous proteins have physiological roles as protective, connective or structural materials. Among the fibrous proteins, silks tend to have blocky structures, with crystallizable and amorphous blocks comprised of short, highly repetitive amino acid sequences. In addition, the high glycine content of silks allows them greater conformational variability than most proteins, thus Bombyx morisilk fibroin is typically polymorphic.

The ability of silk fibroin to adopt multiple conformations and crystal structures makes it difficult to obtain corroborating data using multiple characterization techniques. Differences in sample preparation to accommodate different techniques can also affect the resulting sample structure. Reproducible sample preparation was achieved for IR and TEM experiments by rubbing the dried IR sample with a carbon substrate TEM grid to pick up tiny flakes of solidified peptide.

Twenty-five years ago, one of us postulated the existence of a dynamic mechanism for the selective glial sequestration and removal of effete organelles (mitochondria, vesicles, dense bodies) and leprous bacilli from intact axons of myelinated nerve fibers. A thin cytoplasmic sheet derived from the adaxonal Schwann cell or oligodendrocyte invaginates the axon surface, corralls pockets of axoplasm containing the organelles, and removes the cytoplasmic material by phagocytosis (1). This radical proposal was based on inferences drawn from the seemingly logical sequential assembly of transmission electron micrographs depicting static images of mammalian myelinated nerve fibers in normal and pathologic states. Direct evidence to support this proposal came from the use of light/fluorescence, confocal laser, and/or electron microscopy to trace the fate of fast transported radiolabel injected intraspinally, of red-fluorescent latex nanospheres taken up at a sciatic nerve crush site, and of intramuscularly injected horseradish peroxidase endocytosed by intact synaptic terminals (2,3).

Relapsing fever, a disease characterized by recurrent episodes of high fevers, is caused by geographically distinct spirochetes of the genus Borrelia,transmitted by ticks of the genus Ornithodoros. In the Northwestern United States, the soft tick Ornithodoros hermsi has been identified as the vector for the spirochete Borrelia hermsii. The life cycle of O.hermsi includes larval and multiple nymphal stages prior to full maturation into an adult male or female (Fig.1). Progression into each stage requires a blood-meal typically provided by squirrels and chipmunks, and incidentally humans. Feeding is rapid, lasting 10-60 minutes, and during this time an infected tick can transmit the agent of relapsing fever, B. hermsii. Following ingestion, spirochetes are initially found in the tick midgut. Within 1-3 weeks, they are found in other organs, including the central ganglion and salivary glands. Since saliva is the primary mode of transmission of these bacteria during tick feeding, we assessed by electron microscopy the structural and functional relationships between the spirochetes and the salivary glands.

Connective tissue matrices are quite diversified and include that composing skin, tendon, bone, cartilage, cornea and many others. The main component of the connective tissue matrix is collagen, composing approximately 70% of the dry weight of the human body. More members of the collagen family are discovered each year, with over twenty types described to date. Many of these collagens are tissue specific. In addition to the collagens, the connective tissue matrix is also the residence of epithelial and endothelial basement membranes and many other molecules including a variety of proteoglycans and elastic fiber components. The cells within the matrix are highly differentiated and task specific.

Using immunocytochemical technique applied at the level of the electron microscope, we have focused our resources to understand the structure and functional role of these matrix molecules.

Elevated intraocular pressure (IOP) is the most widely recognized risk factor for glaucoma and the target of nearly all current glaucoma therapy. The goal of our laboratory is to understand mechanism by which elevated IOP results in axonal degeneration in the optic nerve.

In order to study the effects of IOP level on the optic nerve, we have developed a number of methods to modulate IOP in the rat. We sclerose the aqueous humor outflow pathways to elevate IOP for a period of weeks to produce focal optic nerve lesions. This method reproduces many of the pathological characteristics of human glaucoma. A modification of this method uses constant light (CL) housing to stabilize the normally wide circadian IOP oscillations, simplifying the correlation of IOP history with lesion size. However, the CL-stabilized IOP in untreated, fellow eyes is above the normal light phase IOP of 20 mm Hg and close to the normal dark, phase value of 30 mm Hg.

Historically microscopy of the ear has been difficult because it is entirely encased in bone. This not only impeded fixation, embedding, and sectioning of the ear for histology and immunohistochemistry, but also made experimental microscopic observation of the living ear virtually impossible. Numerous recent advancements in microscopy have improved our ability to observe the delicate cellular structures of the ear, as well as utilize high magnification microscopy on living tissue for experimental and physiological studies.

Traditional immunohistochemistry at both the light and electron microscopic levels is now facilitated by better antigen preservation through improvements in decalcification, more permeable plastics, and thousands of commercially produced antibodies. Individual cell surface receptors now can be identified, as well as their upregulation by circulating steroids, drugs, antibodies, and enzymes. Cochlear tissues also can be completely dissociated and the electrophysiology of individual living hair cells recorded with microelectrodes while under microscopic observation.

Recent technical advances in the ability to attach an endogenously fluorescent protein sequence—i.e., green fluorescent protein or GFP and its derivatives--to any protein of experimental interest promises to mark a new era of progress in the study of protein targeting. Bringing these new tools to bear on neurons of the central nervous system has been challenging, however, because they have a very complex structure and are relatively difficult to transfect because they are post-mitotic.

We use two cell culture approaches to characterize protein trafficking within neurons of the central nervous system in vitro. The first is a dissociated culture of hippocampal neurons from embryonic (El8) rats which is especially suited to analysis by conventional light microscopy because these neurons are grown on glass coverslips at low density. Neurons cultured in this way develop a morphology comparable to that seen in vivo and permit the establishment of axons and dendrites to be analyzed by time-lapse microscopy.

Parkinson's disease is a progressive disorder that is characterized by degeneration of the dopamine containing neurons located within the midbrain (substantia nigra). There is also substantial loss of dopamine within nerve terminals located within the striatum which originate from those dopamine neurons. Current therapy involves administration of the precursor to dopamine, namely l-dopa. This chemical is taken up into the brain and then converted to dopamine. Although replacement of dopamine is effective over the first few years, other movement disorders are associated with longterm l-dopa therapy. The l-dopa induced dyskinesias limit the usefulness of this type of therapy.

Although loss of dopamine is the major neurochemical deficit in Parkinson's disease, other neurotransmitters within the striatum may also be altered. There is a major axonal projection from the cortex to the striatum. The corticostriatal pathway uses the excitatory neurotransmitter, glutamate, and dopamine is known to modulate the activity of glutamatergic synapses

Repeated intermittent administration of cocaine to rodents has been shown to result in behavioral sensitization, or enhanced locomotor activity. Because there are similarities between effects of intermittent cocaine use in humans and sensitization in rats, understanding the neural mechanism underlying sensitization may provide insights into mechanisms of psychopathologies in humans.

There is abundant evidence that the mesolimbic dopaminergic pathways, originating in the ventral tegmental area (VTA) and terminating in both nucleus accumbens (NAc) and prefrontal cortex (PFC), are critically important for development of sensitization to the motor-stimulating effects of cocaine. Evidence also suggests that changes in glutamate (Glu) transmission in the mesolimbic DA pathways are associated with sensitization to cocaine. In recent collaborative studies, we have shown that cocaine administration transiently decreases the density of nerve terminal glutamate immunolabeling within the NAc shell following withdrawal from continuous or intermittent cocaine administration. Locomotor activity was not assessed in either of these studies.

The eye offers the unique possibility of direct visualization of microvessels in readily accessible tissues. Due to the compact anatomy of the eye, different microvascular beds of different embryological origin can be examined in albino mice without traumatic tissue preparation, Epifluorescence microscopy in combination with different fluorescent dyes has been applied. To observe individual cells in vessels, rhodamine 6G can be used to stain leukocytes and platelets, and acridine orange stains nuclei of leukocytes and endothelial cells. Fluorescein-isothiocyanate (FITC)-dextran labels plasma.

Iris, limbus, conjunctival and choroidal vessels under normal and inflammatory conditions (endotoxin-induced uveitis) were examined in BALB/c mice and Lewis rats. Digital video technology can be applied to intravital microscopy with great benefit: video quality remains on a high level and the amount of time for the quantification procedure and the need of expensive software is reduced compared to classical video recording.

Pericytes are cells of mesodermal origin that intimately surround most types of blood capillaries as well as postcapillary venules and precapillary arterioles (smooth muscle cells are found in the walls of larger vessels). Although abnormalities of capillary endothelial cells have been described in diseases such as diabetes, arterial hypertension, autoimmune inflammatory myopathies and also in the paraneoplastic phenomenon, much less is known about morphology of pericytes and its implications in the microvascular structure in cancers, particularly those arising in the gastrointestinal tract. In this work we report the pericyte ultrastructural pathology in human gastrointestinal adenocarcinomas.

Surgically resected specimens from areas of tumor center and periphery were obtained from thirteen patients (seven females and six males) between 44 and 76 years of age (mean 61.92 years), with a histopathological diagnosis of gastrointestinal adenocarcinoma. Immediately after resection, tissue samples were processed by routine transmission electron microscopy techniques and observed in Hitachi H-500 and H-7100 electron microscopes.

The Derm Imaging Center uses various light and electron microscopic techniques to determine meaningful morphologic differences in skin samples received from multiple investigators. Qualitative comparisons required laborious hand measurements, which, in time gave way to computer assisted image capture, enhancement and analysis. The ability to attach a numerical value to a morphologic observation has made quantification an expected component of the experimental results. Laboratory personnel are now spending more time in front of computers than microscopes. This fact prompted a reevaluation of our current methods resulting in a faster, user-friendly computer assisted imaging system.

One software program that has become ubiquitous within the field of scientific imaging is Adobe® Photoshop®. Although a multitude of different image capture and analysis software programs are in use, a version of Photoshop® can invariably be found residing in most laboratories involved in imaging. A disadvantage of many image analysis software programs is the lack of image enhancement capability that we have grown to know and love within the Photoshop® environment.

Old-growth Douglas-fir trees in the Pacific Northwest are venerable giants that often live for 500 years and reach heights of over 75 meters. Their needles are relatively ephemeral and small but have the important role of interacting with the atmosphere in order to transpire and photosynthesize. Within the photosynthetic mesophyll tissue of Douglas-fir needles, there are large, non-living cells with lignified secondary cell walls that are known as astrosclereids. Apparent channels in the secondary wall may provide a route for exchange or transport of materials between the astrosclereid lumen and mesophyll cells or the vascular cylinder. Astrosclereids may be involvev d in storage of secondary metabolites such as tannin and may develop in response to fungi, mistletoe, or other pathogens. More knowledge is needed about the development, structure and function of astrosclereids.

Needles were collected from sapling and old-growth Douglas-fir, Pseudotsuga menziesii, (Mirb.) Franco, trees at the Wind River Canopy Crane in Carson, Washington and from three sites in the Cascade Mountains of Oregon in 1997 and 1998.

Lyme disease is a tick borne, multi-system disorder caused by low density systemic infections with the spirochete Borrelia burgdorferi. Without antimicrobial treatment, mammalian infections with these bacteria are persistent and chronic. Recent studies showed that B. burgdorferi can target, invade, and lyse both cultured and primary human B and T cells. Direct interactions between the spirochetes and lymphocytes also leads to adherence of B and T cell antigens on the surface of significant proportions of the bacteria . Adherent lymphocytic antigens inhibit binding of antibodies to prominent B. burgdorferi proteins, and interfere with classic complement-mediated killing, suggesting a possible role for spirochete-lymphocyte interactions in immune evasion.

In order to develop an experimental animal model for assessing spirochete-lymphocyte interactions, B. burgdorferi and primary mouse lymphocytes were co-incubated and examined by electron microscopy. Mononuclear cells were separated from fresh mouse blood by Ficoll gradient centrifugation (ICN, Biomedicals, Aurora, Ohio).