Vascular corrosion replicas provide unique three-dimensional models of both macro- and microcirculatory angio-architecture. In most replication procedures, blood is initially flushed from the vasculature with a low viscosity, non-clotting medium, such as saline, prior to infusion with the unpolymerized resin. While this removes cellular elements from the vessels and prevents coagulation, the chemical characteristics of the saline and the mode in which it is infused can potentially affect vascular smooth muscle. This can be disadvantageous if subsequent distribution of the resin does not faithfully mimic normal perfusion pathways, or if the vascular lumen is either narrowed due to vasospasm or distended due to excessive intravascular pressure. Alternatively, the composition of the saline can be modified to enhance the replication process. This may be done merely to ensure complete filling of the vasculature or to evaluate anatomical foci instrumental in physiological and pharmacological regulation of perfusion distribution.

The architecture of the kidney of birds (and also reptiles) is, unlike in mammalians, mainly determined by the organization of the blood vascular system. Besides arterial supply and venous drainage, the renal portal system forms a main structural component. While the latter was often regarded as a “primitive” feature in the literature, morphological and physiological data reveal its great functional importance.

Microvascular corrosion casts studied in the scanning electron microscope permit the visualization of minute vessels, retaining their 3D-arrangement. Additionally, when compared with graphical reconstructions of serial sections, this method avoids several inherent artifacts like fixation and dehydration shrinkage as well as the compression of the object by the sectioning blade. Most of the studies on avian kidneys with this technique used the domestic chicken as a model. In order to provide additional material for comparative and functional studies, data on the intrarenal vascular structure of other species are required.

On the basis of ultrastructural, biochemical, cytochemical, and electro-physiological evidence, the stria vascularis, a highly vascular epithelium of the mammalian cochlea, has been implicated as one site of endolymph synthesis. It would seem natural to suspect that its highly developed counterpart in the avian cochlea, the tegmentum vasculosum (TV), might have a similar function. This study utilizes routine light and electron microscopy, biochemistry, cytochemistry, and vascular corrosion casting to describe the structure and blood supply to the (TV) in the duckling and provide evidence for its involvement in endolymph synthesis.

Four to 16 week-old ducklings (Anas platyrhyncos)were anesthetized and anticoagulated and perfused via the common carotid arteries with buffered, 2% glutaraldehyde for routine light microscopy or transmission or scanning electron microscopy, or with Mercox resin for vascular corrosion casting. Casts were macerated in 5% KOH and warm water to remove tissue, cleaned in formic acid and water, dried by lyophilization, mounted on stubs and viewed at 10-20 kv by SEM.

Growth of malignant tumors relies on development of new vessels from the existing vessels, a process called angiogenesis. Little is known about the pattern of chronic vascular growth in the human germ cell testicular cancer. To shed light on this topic, we injected human CRL-2073 testicular cancer cells or saline (sham treated mice) into the testes of SCID-mice and studied the growth of the tumor's vasculature using intravital video microscopy (IVM) on days 7, 14, 21, 28 and 37 after injection. On each day, 4 mice were studied. To better identify microvessels, fluorescein isothiocyanate-dextran (FITC) was injected i.v. prior to IVM. After IVM, one testis was cast with Mercox and studied in a scanning electron microscope (SEM), the other was used for histology. IVM images were transferred to the computer and analyzed using the Lucia morphometry software.

The significance of angiogenesis and the vascular architecture have been stressed in numerous studies of the structure and biological properties of the tumor vasculature and blood flow (Folkman and D'Amore, 1996; Jain, 1988). The important question as to whether the vascular architecture of an individual tumor is tumor type specific has been controversial. This is due, at least in part, to the methodologies used. Most reports confine themselves to qualitative observations and comparisons of gross vascular patterns in host and tumor, or to blood vessel density, length and diameter measurements, which in turn vary with the staining and counting techniques.

We studied the microvascular architecture of four different tumor cell lines (CaX, CaNT, SaS, HEC- 1B) in order to determine whether there is a characteristic vascular pattern for different tumor types and whether it differs significantly from two normal tissues, muscle and gut.

A method for producing plastic castings of the internal structure of hard tissue has been described by Marten et al. (1978). Although they examined dentine, this technique could also be used to examine other hard tissue such as bone (Weber, 1983). The aim of our study is to expose the true threedimensional relationships between the internal structures of the compact bone and these microstructural changes of the mandible in the aging rats.

Nine Wistar male rats were used in this study and divided into 3 groups as follows: 3 weeks-old rats as young stage, 12 weeks-old as adult stage and 80 weeks-old as old stage. All rats were perfused with 2.5% glutaraldehyde via the ascending aorta. In one rat for each group, the mandible was decalcified by 10% EDTA and embedded in paraffin. 10 μm sections were stained with Schmorl’s staining method.

The lung is supplied by pulmonary and bronchial arteries. Unilateral ligation of a main pulmonary artery results in bronchial vascular expansion and new anastomoses between the bronchial and pulmonary circulations. The form and location of this expansion is the subject of this project.

We ligated the left pulmonary of 15 rats and killed 3 rats 1,2,4, 6, and 8 weeks after the ligation. We studied 3 control animals that did not undergo ligation. We cast the vasculature of the lungs with methyl methacrylate and examined both the right and left lungs by light and scanning electron microscopy.

We found that the expansion and anastomoses occurred in and near the bronchovascular bundles and along the pleura, even though the rat pleura is supplied by pulmonary vessels. Near large pulmonary arteries, the junctional and alveolar capillaries were irregular, flattened, and had lateral outbulgings. The diameters varied within short lengths.

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.