Use of specular microscopy to determine corneal endothelial cell morphology and morphometry in enucleated cat eyes

The purpose of this study was to investigate the effect of age on endothelial morphology and morphometry in cats. The corneal endothelium was studied using a contact specular microscope. A total of 18 cats (Felis catus Linnaeus, 1758) were evaluated in this study. The subjects were divided into three groups of six cats each in function of age: G1 (1 to 3 months old), G2 (5 to 12 months old), and G3 (24 to 40 months old). The examination presented data as endothelial cell density (ECD), average cell area, corneal thickness, polymegathism, and pleomorphism. Results revealed ECD decrease in corneas of normal cats with age, as well as a corresponding increase in endothelial cell area and pleomorphism. The present work suggests that the endothelial parameters evaluated change with advancing age.

Identification of psoralen loaded PLGA microspheres in rat skin by light microscopy

Drug delivery systems involving the use of polymers are widely studied and discovery of biocompatible polymers has become the focus of research in this area. Psoralen loaded poly(DL-lactide-co-glycolide) (PLGA) microspheres to be used in PUVA therapy (psoralen and UVA irradiation (ultraviolet A, 320-400 nm) of psoriasis were identified in paraffin sections by histological analysis. The psoralen loaded PLGA microspheres were prepared using the solvent evaporation technique. They were spherical and possessed an external smooth surface as observed by scanning electron microscopy (SEM) analysis. This study describes a modification in the routine preparation of microsphere samples for examination by light microscopy. The changes involved fixative agents and/or stains allowing the identification of microspheres containing a non-fluorescent material. The preservation and identification of microspheres in tissues for histological processing in paraffin was greatly improved by these modifications as proven by our results. (c) 2007 Elsevicr Ltd. All rights reserved.

Electron microscopy study of lizard spermiogenesis in Tropidurus torquatus (Lacertilia)

In the course of an investigation on lizard spermiogenesis, the authors have observed events connected with the differentiation of the acrosome and middle-piece of the spermatozoa. Some differences from other reptilians were found as well as: the presence of a subacrosomal space, the absence of the fibrous sheath in the middle-piece, and a very short neck in the mature spermatozoa.

Paracentric inversion involving a NOR-bearing chromosome of rainbow trout (Oncorhyncus mykiss): Electron microscopy studies of the synaptonemal complex

Cytogenetic studies conduced on a sample of 19 specimens of rainbow trout (Oncorhyncus mykiss) showed that 6 presented two chromosomes with a single subterminal AgNOR on the short arms and 13 presented one chromosome with a single subterminal Ag-NOR and a second chromosome with two small subterminal Ag-NORs. Synaptonemal complex studies showed the presence of a pairing failure involving the two lateral elements (LEs) of the NOR-bearing chromosomes only in those specimens with two different NOR-bearing chromosomes, suggesting that the chromosomes with two Ag-NORs originated from a paracentric inversion involving a terminal segment of the original NOR-bearing chromosome. A comparative analysis between three normal and three heterozygous fishes suggest that in the latter group the LEs of the NOR-bearing chromosomes initiate the synaptic process in a more delayed manner, the synapsis develops more quickly, and the nucleolus stays associated with chromosomes for a longer time.

The structure of the human temporomandibular joint disc: A scanning electron microscopy study

The articular disc of the temporomandibular joint was studied in fetuses (16 to 39 weeks of intrauterine life), infants (up to 4 months of age), dentulous adults (aged 30 to 39 years), and completely edentulous adults (aged 60 to 69 years) by scanning electron microscopy. The constituent bundles of collagen fibers were stratified and were oriented anteroposteriorly, laterolaterally, and obliquely in the middle portion of the disc. A ring of laterolateral bundles constituted the main feature of the thick posterior portion. In the anterior portion of the disc, the fibers were anteroposteriorly and obliquely oriented. On the superior and inferior surfaces of the disc, a thin layer of perpendicularly arranged collagen fibers covered the underlying, thick, laterolateral oriented collagen fibers.

Morphological aspects of the mid-palatal suture in the human foetus: A light and scanning electron microscopy study

Morphological features of the mid-palatal suture were studied in human foetuses from 4 to 9 months of intra-uterine life. The foetuses were divided into three age groups, GI (16-23 weeks), GII (24-31 weeks) and GIII (32-39 weeks). The mid-palatal suture in GI foetuses is rectilineal in form with a wide space between the palatal processes of the maxilla. The suture has a sinuous nature in GII and GIII foetuses due to growth of the bone processes crossing the mid-line. A wide zone of cellular proliferation observed in GI narrows in GII and GIII foetuses. The imbricating nature of the suture in GII and GIII is caused by bone growth adjacent to the mid-palatal suture. Sharpey's fibres, emerging from the bone processes, run to the median region of the mid-palatal suture and are observed from GI foetuses onwards. The collagen fibres of the mid-palatal suture are orientated transversely under the oral epithelium and exhibit a regular meshwork with a predominance of sagittal fibres in the median region of the suture. These fibres are orientated transversely and obliquely at the junction with the nasal septum.

Surface amorphization in diamond turning of silicon crystal investigated by transmission electron microscopy

Silicon crystal exhibits a ductile regime during machining prior to the onset of fracture when appropriate cutting conditions are applied. The present study shows that the ductile regime is a result of a phase transformation which is indirectly evidenced by the amorphous phase detected in the machined surface. Transmission electron microscopy (TEM) planar view studies were successfully performed on monocrystalline silicon (1 0 0) single point diamond turned. TEM electron diffraction patterns show that the machined surface presents diffuse rings along with traces of crystalline material. This is attributed to crystalline silicon immersed in an amorphous matrix. Furthermore, only diffuse rings in the diffraction patterns of the ductile chip are detected, indicating that it is totally amorphous. © 2000 Elsevier Science B.V. All rights reserved.

Scanning electron microscopy study of the choroid plexus in the monkey (Cebus apella apella)

The cells of the choroid plexus of the lateral ventricles of the monkey Cebus apella apella were examined through scanning electron microscopy at contributing to the description of such structures in primates. The animals were anesthetized previously with 3% hypnol intraperitoneally and after perfusion with 2.5% glutaraldehyde, samples of the choroid plexus were collected after exhibition of the central portion and inferior horn of the lateral ventricles. The ventricular surface of those cells presents globose form as well as fine interlaced protrusions named microvilli. Among those, it is observed the presence of some cilia. Resting on the choroid epithelial cells there is a variable number of free cells, with fine prolongations which extend from them. They are probably macrophages and have been compared to Kolmer cells or epiplexus cells, located on choroid epithelium. The choroid plexus of the encephalic lateral ventricles of the monkey Cebus apella apella at scanning electron microscopy is similar to that of other primates, as well as to that of other species of mammals mainly cats and rats, and also humans.

Corneal endothelium of the Magellanic penguin (Spheniscus magellanicus) by scanning electron microscopy

The corneal endothelium is essential for the maintenance of the corneal transparency. The aim of this study was to examine the morphology of the endothelial surface and perform morphometric analysis of the normal corneal endothelial cells of the Magellanic penguin (Spheniscus magellanicus) using scanning electron microscopy. The present work demonstrates that the corneal endothelium of the Magellanic penguin is similar to those described in other vertebrates. Copyright 2005 by American Association of Zoo Veterinarians.

Sharpening of periodontal instruments with different sharpening stones and its influence upon root debridement--scanning electronic microscopy assessment

The objective of this study was to evaluate, through scanning electronic microscopy, the effect of sharpening with different sharpening stones on the cutting angle of periodontal curettes (Gracey 5-6), and the influence on root surfaces after debridement and planing. The experimental model consisted of two different phases. In the first, the cutting angles of fifteen stainless steel Gracey 5-6 curettes were analyzed under a scanning electronic microscope after being sharpened with different types of stones. In the second phase, the root surfaces of 25 newly extracted teeth were evaluated with a scanning electronic microscope after being debrided with curettes sharpened with different stones. Analysis of the results showed that the synthetic stones (aluminum oxide and carborundum) are more abrasive and produce more irregular cutting angles, whereas Arkansas stones are less abrasive and produce smoother and more defined cutting angles. There was no significant statistical differences among the five groups tested with regard to the degree of irregularity of the root surfaces after instrumentation.

Scanning electron microscopy evaluation of the effect of etching agents on human enamel surface

Acid etching promotes microporosities on enamel surface, which provide a better bonding surface to adhesive materials. The purpose of this study was to comparatively analyze the microstructure of enamel surface after etching with 37% phosphoric acid or with two self-etching primers, Non-rinse conditioner (NRC) and Clearfil SE Bond (CSEB) using scanning electron microscopy. Thirty sound premolars were divided into 3 groups with ten teeth each: Group 1: the buccal surface was etched with 37% phosphoric acid for 15 seconds; Group 2: the buccal surface was etched with NRC for 20 seconds; Group 3: the buccal surface was etched with CSEB for 20 seconds. Teeth from Group 1 were rinsed with water; teeth from all groups were air-dried for 15 seconds. After that, all specimens were processed for scanning electron microscopy and analyzed in a Jeol 6100 SEM. The results showed deeper etching when the enamel surface was etched with 37% phosphoric acid, followed by NRC and CSEB. It is concluded that 37% phosphoric acid is still the best agent for a most effective enamel etching.

Charge density alterations in human hair fibers: An investigation using electrostatic force microscopy

A new method for high-resolution analyses of hair surface charge density under ambient conditions is presented in this paper. Electrostatic force microscopy (EFM) is used here to analyze changes in surface charge density in virgin hair, bleached hair, and hair treated with a cationic polymer. The atomic force microscopy technique is used concomitantly to analyze morphological changes in hair roughness and thickness. The EFM images depict exactly how the polymer is distributed on the surface of the hair fiber. The EFM's powerful analytical tools enabled us to evaluate the varying degrees of interaction between the hair fiber surface charge density and the cationic polymer. The surface charge density and the polymer's distribution in the hair fibers are presented in the light of EFM measurements. © 2006 Society of Cosmetic Scientists and the Socièété Française de Cosmétologie.