Structural Characteristics of the Lens in Presenile Cataract.

The purpose of this work is to examine the structure of the anterior lens epithelial cells (aLECs) of presenile idiopathic cortical cataract to investigate the possible structural reasons for its development. The anterior lens capsules (aLCs: basement membrane and associated lens epithelial cells) were obtained from routine uneventful cataract surgery of 5 presenile cataract patients (16 and 41 years old women and 29, 39, and 45 years old men). None of the patients had family history of cataract, medication, or trauma and they were otherwise healthy. In addition, the patients did not have any other abnormal features in the ocular status except cataract. The aLCs were prepared for scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The most prominent abnormal features observed by SEM for all 5 studied presenile cataract patients were the changes of the aLECs structure with the dents, the selective concavity of some LECs, at their apical side centrally toward the nucleus. In addition, TEM showed the thinning of the lens epithelium with the segmentally concave cells and the compressed and elongated nuclei. Abnormal and distinguishable structural features were observed in the anterior lens epithelium aLECs in all 5 patients with presenile cataract. Disturbed structure of aLECs, regularly present in presenile cataract type is shown that might be associated with water accumulation in the presenile idiopathic cortical cataract lens.

Classical lepidopteran wing scale colouration in the giant butterfly-moth Paysandisia archon.

The palm borer moth Paysandisia archon (Castniidae; giant butterfly-moths) has brown dorsal forewings and strikingly orange-coloured dorsal hindwings with white spots surrounded by black margins. Here, we have studied the structure and pigments of the wing scales in the various coloured wing areas, applying light and electron microscopy and (micro)spectrophotometry, and we analysed the spatial reflection properties with imaging scatterometry. The scales in the white spots are unpigmented, those in the black and brown wing areas contain various amounts of melanin, and the orange wing scales contain a blue-absorbing ommochrome pigment. In all scale types, the upper lamina acts as a diffuser and the lower lamina as a thin film interference reflector, with thickness of about 200 nm. Scale stacking plays an important role in creating the strong visual signals: the colour of the white eyespots is created by stacks of unpigmented blue scales, while the orange wing colour is strongly intensified by stacking the orange scales.

Anterior lens epithelium in cataract patients with retinitis pigmentosa - scanning and transmission electron microscopy study.

PURPOSE: In retinitis pigmentosa (RP) patients, relatively minor lens opacity in central part of posterior pole of the lens may cause disproportionate functional symptoms requiring cataract operation. To investigate the possible structural reasons for this opacity development, we studied the structure of the lens epithelium of patients with RP. METHODS: The anterior lens capsule (aLC: basement membrane and associated lens epithelial cells, LECs) was obtained from cataract surgery and prepared for scanning and transmission electron microscopy (SEM and TEM). RESULTS: Both SEM and TEM show a number of abnormal features in the anterior lens epithelium of cataract patients with RP. The abnormalities appear mainly as holes, thinning and degradation of the epithelium, with the dimensions from <1 µm to more than 50 µm. Other types of holes in size up to 20 µm were seen that may be formed by gradual stretching of the lens epithelium. Another type of abnormalities was cracks that were seen between adjacent LECs, with dimensions 0.1-2 µm × up to 10 µm. CONCLUSIONS: Abnormal structural features were observed in the anterior lens epithelium that may cause water influx into the lens. This may lead to clouding along the water clefts leading towards the posterior pole in the RP cataractous lens. We suggest that the lens epithelium has a role in the development of the cataract in patients with RP.

Anterior lens epithelium in intumescent white cataracts - scanning and transmission electron microscopy study.

PURPOSE: Our purpose was to study the structure of the lens epithelial cells (LECs) of intumescent white cataracts (IC) in comparison with nuclear cataracts (NC) in order to investigate possible structural reasons for development of IC. METHODS: The anterior lens capsule (aLC: basement membrane and associated LECs) were obtained from cataract surgery and prepared for scanning electron microscopy (SEM) and transmission electron microscopy (TEM). RESULTS: We observed by SEM that in IC, LEC swelling was pronounced with the clefts surrounding the groups of LECs. Another structural feature was spherical formations, that were observed on the apical side of LEC's, towards the fibre cell layer, both by SEM and TEM. Development of these structures, bulging out from the apical cell membrane of the LEC's and disrupting it, could be followed in steps towards the sphere formation. The degeneration of the lens epithelium and the structures of the aLC in IC similar to Morgagnian globules were also observed. None of these structural changes were observed in NC. CONCLUSIONS: We show by SEM and TEM that, in IC, LECs have pronounced structural features not observed in NC. This supports the hypothesis that the disturbed structure of LECs plays a role in water accumulation in the IC lens. We also suggest that, in IC, LECs produce bulging spheres that represent unique structures of degenerated material, extruded from the LEC.

Anterior lens epithelial cells attachment to the basal lamina.

PURPOSE: To study the structure of the anterior lens epithelial cells (aLECs) and the contacts of the aLECs with the basal lamina (BL) in order to understand their role in the lens epithelium's function. METHODS: The aLCs (BL and associated aLECs) were obtained from routine uneventful cataract surgery, prepared for and studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and confocal microscopy. RESULTS: SEM shows that the basal surface of the aLECs (~10-15 µm) is with aLECs foldings (~1-3 µm) and extensions (~0.5-3 µm) attached to the BL. Confocal microscopy images of the basal sections of the aLECs after membrane staining also suggest that the basal part of aLECs has foldings (~1-3 µm). TEM shows in the aLECs basal parts, towards BL, the structures that look like entanglement (~1-4 µm). In cases where there is a swelling of the cytoplasm and offset of the aLECs from the BL, individual extensions (~0.5-2 µm) that extend to the BL are visible by TEM. CONCLUSIONS: We provide detail evidence about the structural organization of the aLECs, in particular about their basal side which is in contact with the BL. This is supported by the complementary use of three techniques, SEM, TEM and confocal microscopy, each of them showing the same morphological features, the extensions and the entanglements of the aLECs cytoplasmic membrane at the border with the BL. The basal surface of the aLECs is increased. It suggests the functional importance of the contact between aLECs and BL.

Morphological and proliferative studies on ex vivo cultured human anterior lens epithelial cells - relevance to capsular opacification.

PURPOSE: To determine the structural characteristics of lens epithelial cells (LECs) found on the anterior portion of the lens capsule and their pluripotency, proliferating and migrating potential when grown ex vivo with relevance to posterior capsular opacification (PCO) after cataract surgery. METHODS: The explants of anterior portion of the lens capsule consisting of monolayer of LECs were obtained from uneventful cataract surgery and were cultivated under adherent conditions. The size and shape of the outgrowing cells were recorded by scanning electron microscopy (SEM), while their migration and proliferation potential were followed using light microscopy. Positivity for proliferation (Ki-67)- and pluripotency (Sox2)-specific markers were tested by immunofluorescent staining. RESULTS: The proliferation and migration of anterior portion of the lens capsule's LECs filling up the denuded and reverse side regions of the lens capsule as well as their growth on glass culture surfaces could be followed by light microscopy and SEM, while the distribution of LECs and their morphology could be analysed in detail by SEM. The expression of Ki-67 and Sox2 in LECs growing adherently on human anterior portion of the lens capsule could also be detected. CONCLUSIONS: Classic light microscopy and SEM can be used to show that human anterior portion of the lens capsule harbours LECs that can proliferate and migrate, suggesting their pluripotency or putative stem cell nature. Similarly, morphological techniques can be used to study PCO and the effect different drugs or physical treatments have against PCO development.

Calu-3 model under AIC and LCC conditions and application for protein permeability studies.

Broad area of respiratory epithelium with mild surface conditions is an attractive possibility when trans-mucosal delivery of protein drugs is considered. A mucus and cellular barrier of respiratory epithelium can be modelled in vitro by Calu-3 cell line. We have monitored morphology and barrier properties of Calu-3 culture on permeable supports while developing into liquid covered or air interfaced and mucus lined cellular barrier. Besides morphological differences, cultures differed in electrical resistance and permeability to proteins as well. The accelerated permeability to proteins in these models, due to permeability modulator MP C16, was examined. The effect on electrical resistance of cellular layer was rapid in both cultures suggesting easy access of MP C16 to cells even though its overall impact on cell permeability was strongly reduced in mucus covered culture. Differences in properties of the two models enable better understanding of protein transmucosal permeability, suggesting route of transport and MP C16 modulator action.

Effects of prolonged exposure to cold on the spontaneous activity of two different types of filiform sensilla in Pyrrhocoris apterus.

We recorded the spontaneous activity of T1 and T2 filiform sensilla from October to May in Pyrrhocoris apterus acclimatized to outdoor conditions. The aim of the study was to determine how prolonged exposure to cold affects two closely related mechanosensitive sensilla. We recorded the activity at seven temperatures from 5 to 35 °C. In both sensilla types the activity level was reduced during winter, which correlated to changes in acclimatization temperature (r = 0.7), the reduction was greater at high recording temperatures, and the effects of exposure to cold were reversed by transferring the animals indoors. However, T1 activity always increased monotonically, if the recording temperature was increased from 5 to 35 °C, whereas T2 activity in cold-acclimatized animals increased to temperatures between 20 and 30 °C and then started decreasing. As a result, the temperature sensitivity of the activity was reduced more profoundly in T2 sensilla (in T2 Q10 was reduced from 3.5 in October to 1.4 in January, whereas in T1 it was reduced from 2.5 to 2.2). In conclusion, we have shown that prolonged exposure to cold does affect filiform sensilla; however, the effect is significantly different in the two sensilla types.

Multiple mechanisms generate the resting activity of filiform sensilla in the firebug (Pyrrhocoris apterus L.; Heteroptera).

The resting activity was studied in filiform sensilla of the firebug (Pyrrhocoris apterus). Three functional types (T(1), T(2) and T(3)) were detected on the abdomen. A resting discharge of nerve impulses is present in all-always in types T(1) and T(2) and occasionally in type T(3). In T(1) the mean rate is 57, in T(2) 3.3 and in T(3) 0.5 imp/s. Shortening the hair length had a negligible effect on the resting discharge, which indicates an intrinsic origin. The resting activity is highly temperature dependent. In T(1), the activation energy was 56.8, in T(2) 84 and in T(3) 61.4 kJ/mol (Q (10): 2.27, 5.6 and 5.5, respectively). Such values are typical for mechano-transduction, suggesting the involvement of the transduction mechanism itself. The destruction of the hair base in T(1) caused halving of the original discharge rate and shifted the discharge to a regular interval mode. The activation energy decreased to 38 kJ/mol. The destruction of the hair bases in T(2) and T(3) completely abolished the discharge. It appears that at least two mechanisms are involved in the generation of the resting activity in T(1) units while only one can be assumed in case of T(2) and T(3).

Focused ion beam/scanning electron microscopy studies of Porcellio scaber (Isopoda, Crustacea) digestive gland epithelium cells.

The focused ion beam (FIB) was used to prepare cross sections of precisely selected regions of the digestive gland epithelium of a terrestrial isopod P. scaber (Isopoda, Crustacea) for scanning electron microscopy (SEM). The FIB/SEM system allows ad libitum selection of a region for gross morphologic to ultrastructural investigation, as the repetition of FIB/SEM operations is unrestricted. The milling parameters used in our work proved to be satisfactory to produce serial two-dimensional (2-D) cuts and/or three-dimensional (3-D) shapes on a submicrometer scale. A final, cleaning mill at lower ion currents was employed to minimize the milling artifacts. After cleaning, the milled surface was free of filament- and ridge-like milling artifacts. No other effects of the cleaning mill were observed.

Focused ion beam for microscopy and in situ sample preparation: application on a crustacean digestive system.

We prove that the focused ion beam (FIB) machine can be used as a microscope and as an in situ cutting device for tissue and cells. For the first time we obtain high-resolution ion images, complemented by electron imaging of different animal tissues both from uncoated and coated samples. In our study, we select the digestive system of Porcellio scaber (isopoda, crustacea) as a test system for FIB microscopy and in situ sample preparation. After the milling operation, some of the ultrastructural elements of hepatopancreatic cells can clearly be recognized. Also, FIB operation reveals significant differences in structural integrity between the apical and basal parts of hepatopancreatic cells, which have not been observed before by classical microscopy techniques. FIB microscopy and in situ sample preparation have advantages over classical microscopy techniques because of: 1. in situ site-specific 2-D sectioning and imaging of subsurface microstructures; 2. no need to embed the sample prior to sectioning; and 3. a wide range of magnifications while imaging the same sample.

Uptake of chromium(III) and chromium(VI) compounds in the yeast cell structure.

The study presented in this article investigated the influence of different Cr(III) and Cr(VI) compounds in the cultivation medium on the uptake and localization of chromium in the cell structure of the yeast Candida intermedia. The morphology of the yeast cell surface was observed by the scanning electron microscopy. Results demonstrated that the growth inhibitory concentration of Cr(III) in the cultivation medium induced changes in the yeast cell shape and affected the budding pattern, while inhibitory concentration of Cr(VI) did not cause any visible effects on morphological properties of the yeast cells. The amount of total accumulated chromium in yeast cells and the distribution of chromium between the yeast cell walls and spheroplasts were determined by atomic absorption spectroscopy. No significant differences were found neither in total chromium accumulation nor in the distribution of chromium in yeast cell walls and spheroplasts between the two of Cr(VI) compounds. Conversely, substantial differences between Cr(III) compounds were demonstrated in the total uptake as well as the localization of chromium in yeast cells.