Video microscopy as an alternative method for somatic cell count in milk

This paper presents an alternative method to estimate somatic cell count (SCC) in cows' milk. SCC is an important indicator in the detection of inflammatory reactions within the udder in cows and Direct Optical Microscopy (DOM) is the present reference method for SCC but, owing to its dependence on human operators, it is extremely costly, time-consuming and potentially subjective. The industrial method of choice is Epifluorescence (EF), which has the potential for impressive throughput and acceptable precision, but requires huge inversions and handling of highly toxic reactives and waste. In this paper, an advantageous method that involves application of a low-cost Video Microscopy (VM) system is analysed and discussed, including a comparison between DOM and VM, and an example of application of both methods to evaluate EF counts. We conclude that VM is sufficiently precise and very cheap to implement and operate.

Physical enviroment of 2-D animal cell aggregates formed in a short pathlength ultrasound standing wave trap

2-D mammalian cell aggregates can be formed and levitated in a 1.5 MHz single half wavelength ultrasound standing wave trap. The physical environment of cells in such a trap has been examined. Attention was paid to parameters such as temperature, acoustic streaming, cavitation and intercellular forces. The extent to which these factors might be intrusive to a neural cell aggregate levitated in the trap was evaluated. Neural cells were exposed to ultrasound at a pressure amplitude of 0.54 MPa for 30 s; a small aggregate had been formed at the center of the trap. The pressure amplitude was then decreased to 0.27 MPa for 2 min, at which level the aggregation process continued at a slower rate. The pressure amplitude was then decreased to 0.06 MPa for 1 h. Temperature measurements that were conducted in situ with a 200 microm thermocouple over a 30 min period showed that the maximum temperature rise was less than 0.5 K. Acoustic streaming was measured by the particle image velocimetry method (PIV). It was shown that the hydrodynamic stress imposed on cells by acoustic streaming is less than that imposed by gentle preparative centrifugation procedures. Acoustic spectrum analysis showed that cavitation activity does not occur in the cell suspensions sonicated at the above pressures. White noise was detected only at a pressure amplitude of 1.96 MPa. Finally, it was shown that the attractive acoustic force between ultrasonically agglomerated cells is small compared with the normal attractive van der Waals force that operates at close cell surface separations. It is concluded that the standing wave trap operates only to concentrate cells locally, as in tissue, and does not modify the in vitro expression of surface receptor interactions.

Intravital microscopic observations of 15-microm microspheres lodging in the pulmonary microcirculation

Vascular infusions of 15-microm-diameter microspheres are used to study pulmonary blood flow distribution. The sites of microsphere lodging and their effects on microvascular perfusion are debated but unknown. Using intravital microscopy of the subpleural surface of rat lungs, we directly observed deposition of fluorescent microspheres. In a pump-perfused lung model, approximately 0.5 million microspheres were infused over 30 s into the pulmonary artery of seven rats. Microsphere lodging was analyzed for the location in the microvasculature and the effect on local flow after lodging. On average, we observed 3.2 microspheres per 160 alveolar facets. The microspheres always entered the arterioles as singlets and lodged at the inlets to capillaries, either in alveolar corner vessels or small arterioles. In all cases, blood flow continued either around the microspheres or into the capillaries via adjacent pathways. We conclude that 15-microm-diameter microspheres, in doses in excess of those used in typical studies, have no significant impact on pulmonary capillary blood flow distribution.

Quantification of the magnification and distortion effects of a pediatric flexible video-bronchoscope

BACKGROUND

Flexible video bronchoscopes, in particular the Olympus BF Type 3C160, are commonly used in pediatric respiratory medicine. There is no data on the magnification and distortion effects of these bronchoscopes yet important clinical decisions are made from the images. The aim of this study was to systematically describe the magnification and distortion of flexible bronchoscope images taken at various distances from the object.

METHODS

Using images of known objects and processing these by digital video and computer programs both magnification and distortion scales were derived.

RESULTS

Magnification changes as a linear function between 100 mm (x1) and 10 mm (x9.55) and then as an exponential function between 10 mm and 3 mm (x40) from the object. Magnification depends on the axis of orientation of the object to the optic axis or geometrical axis of the bronchoscope. Magnification also varies across the field of view with the central magnification being 39% greater than at the periphery of the field of view at 15 mm from the object. However, in the paediatric situation the diameter of the orifices is usually less than 10 mm and thus this limits the exposure to these peripheral limits of magnification reduction. Intraclass correlations for measurements and repeatability studies between instruments are very high, r = 0.96. Distortion occurs as both barrel and geometric types but both types are heterogeneous across the field of view. Distortion of geometric type ranges up to 30% at 3 mm from the object but may be as low as 5% depending on the position of the object in relation to the optic axis.

CONCLUSION

We conclude that the optimal working distance range is between 40 and 10 mm from the object. However the clinician should be cognisant of both variations in magnification and distortion in clinical judgements.

Image Stabilization and Registration for Tracking Cells in the Microvasculature

We propose a registration system to be used for tracking cells in intravital video microscopy that 1) stabilizes jitter-the undesired translational displacement of frames due to respiratory movement, etc., and 2) registers frames in a moving field of view (FOV) to allow for cell tracking over an extended range. For the first time, tracking of rolling leukocytes in vivo over a moving FOV is demonstrated. In a fixed FOV, stable background regions are located using a morphological approach. Template subregions are then selected from the stable regions and matched to corresponding locations in a reference frame. We show the effectiveness of the stabilization algorithm by using an active contour to track 15 leukocytes previously untrackable due to jitter. For 30 fixed FOV sequences containing rolling leukocytes, the resulting root-mean-square error (RMSE) is less than 0.5 microm. To align frames in a moving FOV, we present a modified correlation approach to estimate the common region between two consecutive fixed FOVs. We correlate the overlapping regions of the initial frame of the current fixed FOV and the final frame of the previous fixed FOV to register the images in the adjoining moving FOV. The RMSE of our moving FOV registration technique was less than 0.6 mmicrom. In 10 sequences from different venules, we were able to track 11 cells using an active contour approach over moving FOVs.

Raman spectra of dipicolinic acid in crystalline and liquid environments

Raman spectra of dipicolinic acid (DPA) are important for detection of bacterial spores, since DPA and its salts present one of their major components. The implementation of a deeply cooled CCD camera in combination with pulsed excitation at 532 nm allowed measuring well-resolved Raman spectra of the DPA in different forms. Powder preparations, crystals grown from saturated solutions and aqueous solutions of the DPA were studied. The spectral features in different environments and comparison with the spectra obtained by other methods are discussed.

Imaging early macrophage differentiation, migration, and behaviors in live zebrafish embryos

Because zebrafish embryos are transparent, cell behaviors and interactions can be directly imaged noninvasively in live embryos using differential interference contrast-Nomarski light microscopy. We found that the imaging quality can be much improved by coupling differential interference contrast-Nomarski to true (analogical) color video so as to visualize the image in real time on a high-resolution colour video monitor. We explain here how to apply this approach to the in vivo imaging of embryonic macrophages, which constitute a distinct early macrophage lineage, that originates from the rostral-most lateral mesoderm--adjacent to the cardiac field, differentiate in the yolk sac, and rapidly spread in embryonic tissues, although still retaining proliferative capacity.

Visualization and in situ analysis of leukocyte trafficking into the ankle joint in a systemic murine model of rheumatoid arthritis

OBJECTIVE

To describe the kinetics of leukocyte migration into a distal joint during the development of chronic inflammation in a murine model of rheumatoid arthritis (RA), to identify leukocyte subpopulations recruited in the synovial vessels, and to test in real time the effects of an antiinflammatory compound on leukocyte-endothelial cell interactions in the arthritic joint.

METHODS

We used intravital video microscopy (IVM), which was adapted to the microcirculation of the mouse ankle, to monitor the kinetics of leukocyte-endothelium interactions (rolling and firm adhesion) during the onset and progression of proteoglycan-induced arthritis (PGIA), a chronic autoimmune model of RA. Subpopulations of rolling and adherent leukocytes were identified by in vivo immunostaining. Leukocyte extravasation into the ankle joint was verified histologically.

RESULTS

Between the onset of arthritis and the beginning of the destructive phase of PGIA, we found a steady increase in the number of leukocytes that exhibited firm adherence to the endothelium of synovial vessels, which clearly underscores the chronic, self-perpetuating character of joint inflammation in this autoimmune model. We showed, however, that granulocytes, and not T cells, constituted the major cell population that was continuously recruited to the inflamed ankle. Using IVM, we could detect instant changes in leukocyte adhesion behavior in the synovial vessels of the arthritic joint upon administration of a compound that antagonizes leukocyte rolling.

CONCLUSION

IVM of the microcirculation of the mouse ankle could become an essential tool for investigating the mechanisms that regulate leukocyte migration to the joint in systemic models of RA as well as for preclinical testing of antiinflammatory therapies.

Videomicroscopy, image processing, and analysis of whole histologic sections of the human brain

Serial histologic sections of a whole human brain may have extensions of up to 130 x 130 mm within the coronal plane around the temporal lobe. To date, however, technology has not provided a bright field microscope that is able to shift the object holder continuously in the x- and y-direction over such distances and still possess the same optical capabilities as comparable devices. We developed a new light microscope to continuously quantify such sections. We also developed the computing environment for controlling the device and for analyzing the data produced. In principle, we are now able to quantify each neuron of a human brain. The data ultimately will provide the most detailed structural information about the human brain ascertained thus far. Such detailed information of the spatial distribution of neurons is essential to develop realistic models for simulation of large-scale neuronal networks and to investigate the significance of neuronal arrangements with respect to neuronal signal processing in the CNS. After preprocessing of the data produced by the new microscope, we are able to detect lamination patterns in the spatial distribution of gravity centers of cells. Furthermore, morphological features like size of the projection area and mean staining intensity are visualized as a particle process. The particle process presents the sizes and staining intensity of perikaryons and allows a distinction of gray matter and white matter. These results provide evidence that the system works correctly and can be applied to a systematic analysis of a larger sequence of serial histologic sections. The objective of this study is to introduce the very large section analyzing microscope (VLSAM) and to present the initial data produced by the system. Moreover, we will discuss workload and future developments of the parallel image analysis system that are associated with the microscope.

Mosaicing of Confocal Microscopic In Vivo Soft Tissue Video Sequences

Fibered confocal microscopy allows in vivo and in situ imaging with cellular resolution. The potentiality of this imaging modality is extended in this work by using video mosaicing techniques. Two novelties are introduced. A robust estimator based on statistics for Riemannian manifolds is developed to find a globally consistent mapping of the input frames to a common coordinate system. A mosaicing framework using an efficient scattered data fitting method is proposed in order to take into account the non-rigid deformations and the irregular sampling implied by in vivo fibered confocal microscopy. Results on 50 images of a live mouse colon demonstrate the effectiveness of the proposed method.

Automated Method for Tracking Individual Red Blood Cells Within Capillaries to Compute Velocity and Oxygen Saturation

OBJECTIVE

The authors present a new method to track individual red blood cells (RBCs) as they move through capillaries. This method uses a recently developed Measurement and Analysis System for Capillary Oxygen Transport (MASCOT) and the concept of space-time images to track RBCs between consecutive frames of video recordings of the microcirculation.

METHODS

A space-time image displays in a single static image for a single capillary the location of all RBCs as a function of time. Analysis is performed on video tapes of RBC flow through capillaries to obtain velocity of individual cells as they traverse the capillary of interest. A space-time image is generated to track RBCs from one frame to the next and their velocities are computed. Based on the optical density values of each cell obtained from synchronized videotapes at two wavelengths, the oxygen saturation of a cell can be determined. In this manner, oxygen saturation can be tracked for the same cells as they move through the capillary.

RESULTS AND CONCLUSIONS

These measurements, taken together, allow one to determine how much and how fast oxygen is being delivered to the surrounding tissue. This method provides, for the first time, a way to track individual RBCs flowing through capillary networks and study their RBC dynamics and oxygenation.

Visualizing intracellular events in vivo by combined video fluorescence and 3-D electron microscopy

The combination of the capability of in vivo fluorescence video microscopy with the power of resolution of electron microscopy (EM) has been described. This approach is based on such an association of two techniques. An individual intracellular structure can be monitored in vivo, typically through the use of markers fused with green fluorescent protein (GFP), and a "snapshot" of its three-dimensional (3-D) ultrastructure and especially tomographic reconstruction can then be taken at any chosen time during its life cycle. The pitfalls and potential of this approach are discussed.

Intravital intestinal videomicroscopy: Techniques and experiences

Intravital videomicroscopy (IVM) of the gastrointestinal (GI) tract is a sophisticated and powerful technique to directly observe the neurologically intact microvasculature of rats in naive and pathological conditions. We combine IVM with other techniques (i.e., vascular ring tension analysis and colorimetric microsphere determination of whole organ blood flow) to develop a strategy for the systematic analysis of the regulation of GI blood flow in healthy animals and in models of systemic sepsis and resuscitated hemorrhagic shock. We also study the molecular biology of the GI tract (enzyme- or radio-linked immunosorbent assays, fluorescent Greiss assay, and immunoblots) to correlate expression and levels of vascular mediators in tissue and arterial, venous, and portal blood with functional activity of the GI microvascular tree. When combined, these techniques develop a picture of gut pathophysiology at the level of the endothelium, vascular smooth muscle cells, and blood cells in the microcirculation. Our work led us to the general hypothesis that altered microcirculatory function in disease states lies primarily at the level of the interface between vascular and tissue physiology, i.e., the endothelial cell. This review focuses on methods and techniques for studying microvascular function, and concludes with focused reviews of pertinent findings.

Development of advanced image analysis techniques for the in situ characterization of multiphase dispersions occurring in bioreactors

Fermentation bioprocesses typically involve two liquid phases (i.e. water and organic compounds) and one gas phase (air), together with suspended solids (i.e. biomass), which are the components to be dispersed. Characterization of multiphase dispersions is required as it determines mass transfer efficiency and bioreactor homogeneity. It is also needed for the appropriate design of contacting equipment, helping in establishing optimum operational conditions. This work describes the development of image analysis based techniques with advantages (in terms of data acquisition and processing), for the characterization of oil drops and bubble diameters in complex simulated fermentation broths. The system consists of fully digital acquisition of in situ images obtained from the inside of a mixing tank using a CCD camera synchronized with a stroboscopic light source, which are processed with a versatile commercial software. To improve the automation of particle recognition and counting, the Hough transform (HT) was used, so bubbles and oil drops were automatically detected and the processing time was reduced by 55% without losing accuracy with respect to a fully manual analysis. The system has been used for the detailed characterization of a number of operational conditions, including oil content, biomass morphology, presence of surfactants (such as proteins) and viscosity of the aqueous phase.

Suppression of photobleaching-induced artifacts in frequency-domain FLIM by permutation of the recording order

BACKGROUND

Photobleaching can lead to significant errors in frequency-domain fluorescence lifetime imaging microscopy (FLIM). Existing correction methods for photobleaching require additional recordings and processing time and can result in additional noise. A method is introduced that suppresses the effects of photobleaching without the need for extra recordings or processing.

METHODS

Existing bleach correction methods and the method introduced in this report whereby the recording order of the phases is permuted were compared using numerical simulations.

RESULTS

Certain orders were found to make measurements virtually insensitive to photobleaching. At 12 recordings, errors in measured phase and modulation depth decreased by a factor 512 and 393, respectively, compared to recordings using sequential recording order. The optimal order is independent of modulation depth, phase, and extent of photobleaching. Thus, the same order can be used for practically all situations. Application of the method in FLIM measurements of EYFP-transfected HeLa cells was found effectively to suppress photobleaching induced artifacts.

CONCLUSIONS

In view of the ease of implementation, its inherent robustness, and the possibility to still apply existing correction methods afterward, there is no good reason not to use the permuted recording order presented in this report instead of a sequential order.

Velocimetric third-harmonic generation microscopy: micrometer-scale quantification of morphogenetic movements in unstained embryos

We demonstrate the association of third-harmonic generation (THG) microscopy and particle image velocimetry (PIV) analysis as a novel functional imaging technique for automated micrometer-scale characterization of morphogenetic movements in developing embryos. Using a combined two-photon-excited fluorescence and THG microscope, we characterize the optical properties of Drosophila embryos and show that sustained THG imaging does not perturb sensitive developmental dynamics. Velocimetric THG imaging provides a quantitative description of the dynamics of internal structures in unstained wild-type and mutant embryos.

Electro-deformation and poration of giant vesicles viewed with high temporal resolution

Fast digital imaging was used to study the deformation and poration of giant unilamellar vesicles subjected to electric pulses. For the first time the dynamics of response and relaxation of the membrane at micron-scale level is revealed at a time resolution of 30 micros. Above a critical transmembrane potential the lipid bilayer ruptures. Formation of macropores (diameter approximately 2 microm) with pore lifetime of approximately 10 ms has been detected. The pore lifetime has been interpreted as interplay between the pore edge tension and the membrane viscosity. The reported data, covering six decades of time, show the following regimes in the relaxation dynamics of the membrane. Tensed vesicles first relax to release the acquired stress due to stretching, approximately 100 micros. In the case of poration, membrane resealing occurs with a characteristic time of approximately 10 ms. Finally, for vesicles with excess area an additional slow regime was observed, approximately 1 s, which we associate with relaxation of membrane curvature. Dimensional analysis can reasonably well explain the corresponding characteristic timescales. Being performed on cell-sized giant unilamellar vesicles, this study brings insight to cell electroporation. The latter is widely used for gene transfection and drug transport across the membrane where processes occurring at different timescales may influence the efficiency.

Fluorescence imaging for monitoring the colocalization of two single molecules in living cells

The interaction, binding, and colocalization of two or more molecules in living cells are essential aspects of many biological molecular processes, and single-molecule technologies for investigating these processes in live cells, if successfully developed, would become very powerful tools. Here, we developed simultaneous, dual-color, single fluorescent molecule colocalization imaging, to quantitatively detect the colocalization of two species of individual molecules. We first established a method for spatially correcting the two full images synchronously obtained in two different colors, and then for overlaying them with an accuracy of 13 nm. By further assessing the precision of the position determination, and the signal/noise and signal/background ratios, we found that two single molecules in dual color can be colocalized to within 64-100 nm (68-90% detectability) in the membrane of cells for GFP and Alexa633. The detectability of true colocalization at the molecular level and the erroneous inclusion of incidental approaches of two molecules as colocalization have to be compromised at different levels in each experiment, depending on its purpose. This technique was successfully demonstrated in living cells in culture, monitoring colocalization of single molecules of E-cadherin fused with GFP diffusing in the plasma membrane with single molecules of Alexa633 conjugated to anti-E-cadherin Fab externally added to the culture medium. This work established a benchmark for monitoring the colocalization of two single molecules, which can be applied to wide ranges of studies for molecular interactions, both at the levels of single molecules and collections of molecules.

Motion gradient vector flow: an external force for tracking rolling leukocytes with shape and size constrained active contours

Recording rolling leukocyte velocities from intravital microscopic video imagery is a critical task in inflammation research and drug validation. Since manual tracking is excessively time consuming, an automated method is desired. This paper illustrates an active contour based automated tracking method, where we propose a novel external force to guide the active contour that takes the hemodynamic flow direction into account. The construction of the proposed force field, referred to as motion gradient vector flow (MGVF), is accomplished by minimizing an energy functional involving the motion direction, and the image gradient magnitude. The tracking experiments demonstrate that MGVF can be used to track both slow- and fast-rolling leukocytes, thus extending the capture range of previously designed cell tracking techniques.

Simultaneous Imaging of Different Focal Planes in Fluorescence Microscopy for the Study of Cellular Dynamics in Three Dimensions

The imaging of cellular dynamics in three dimensions using a standard microscope is severely limited due to the fact that only one focal plane can be imaged at a given point in time. Here we present a modification of the classical microscope design with which two or more focal planes can be imaged simultaneously. This is achieved by a modification of the emission pathway of a standard microscope. The efficacy of the design is shown by imaging bead samples and an FcRn-green fluorescent protein expressing tubule that leaves a sorting endosome and subsequently exocytoses at the plasma membrane.

Ratiometric intracellular calcium imaging in the isolated beating rat heart using indo-1 fluorescence

Abnormalities in intracellular calcium (Cai2+) handling have been implicated as the underlying mechanism in a large number of pathologies in the heart. Study into the relation between Cai2+behavior and performance of the whole heart function could provide detailed information into the cellular basis of heart function. In this study we describe an optical ratio imaging setup and an analysis method for the beat-to-beat Cai2+videofluorescence images of an indo-1 loaded, isolated Tyrode-perfused beating rat heart. The signal-to-noise ratio and the spatiotemporal resolution (with an optimum of 1 ms and 0.6 mm, respectively) made it possible to register different temporal Cai2+transients together with left ventricle pressure changes. The Cai2+transients showed that Cai2+activation propagates horizontally from left to right during sinus rhythm or from the stimulus site during direct left ventricle stimulation. The indo-1 ratiometric video technique developed allows the imaging of ratio changes of Cai2+with a high temporal (1 ms) and spatial (0.6 mm) resolution in the isolated Tyrode-perfused beating rat heart.

Static and dynamic errors in particle tracking microrheology

Particle tracking techniques are often used to assess the local mechanical properties of cells and biological fluids. The extracted trajectories are exploited to compute the mean-squared displacement that characterizes the dynamics of the probe particles. Limited spatial resolution and statistical uncertainty are the limiting factors that alter the accuracy of the mean-squared displacement estimation. We precisely quantified the effect of localization errors in the determination of the mean-squared displacement by separating the sources of these errors into two separate contributions. A "static error" arises in the position measurements of immobilized particles. A "dynamic error" comes from the particle motion during the finite exposure time that is required for visualization. We calculated the propagation of these errors on the mean-squared displacement. We examined the impact of our error analysis on theoretical model fluids used in biorheology. These theoretical predictions were verified for purely viscous fluids using simulations and a multiple-particle tracking technique performed with video microscopy. We showed that the static contribution can be confidently corrected in dynamics studies by using static experiments performed at a similar noise-to-signal ratio. This groundwork allowed us to achieve higher resolution in the mean-squared displacement, and thus to increase the accuracy of microrheology studies.

Mechanics of transient platelet adhesion to von Willebrand factor under flow

A primary and critical step in platelet attachment to injured vascular endothelium is the formation of reversible tether bonds between the platelet glycoprotein receptor Ibalpha and the A1 domain of surface-bound von Willebrand factor (vWF). Due to the platelet's unique ellipsoidal shape, the force mechanics involved in its tether bond formation differs significantly from that of leukocytes and other spherical cells. We have investigated the mechanics of platelet tethering to surface-immobilized vWF-A1 under hydrodynamic shear flow. A computer algorithm was used to analyze digitized images recorded during flow-chamber experiments and track the microscale motions of platelets before, during, and after contact with the surface. An analytical two-dimensional model was developed to calculate the motion of a tethered platelet on a reactive surface in linear shear flow. Through comparison of the theoretical solution with experimental observations, we show that attachment of platelets occurs only in orientations that are predicted to result in compression along the length of the platelet and therefore on the bond being formed. These results suggest that hydrodynamic compressive forces may play an important role in initiating tether bond formation.

Digital photography: a primer for pathologists

The computer and the digital camera provide a unique means for improving hematology education, research, and patient service. High quality photographic images of gross specimens can be rapidly and conveniently acquired with a high-resolution digital camera, and specialized digital cameras have been developed for photomicroscopy. Digital cameras utilize charge-coupled devices (CCD) or Complementary Metal Oxide Semiconductor (CMOS) image sensors to measure light energy and additional circuitry to convert the measured information into a digital signal. Since digital cameras do not utilize photographic film, images are immediately available for incorporation into web sites or digital publications, printing, transfer to other individuals by email, or other applications. Several excellent digital still cameras are now available for less than 2,500 dollars that capture high quality images comprised of more than 6 megapixels. These images are essentially indistinguishable from conventional film images when viewed on a quality color monitor or printed on a quality color or black and white printer at sizes up to 11x14 inches. Several recent dedicated digital photomicroscopy cameras provide an ultrahigh quality image output of more than 12 megapixels and have low noise circuit designs permitting the direct capture of darkfield and fluorescence images. There are many applications of digital images of pathologic specimens. Since pathology is a visual science, the inclusion of quality digital images into lectures, teaching handouts, and electronic documents is essential. A few institutions have gone beyond the basic application of digital images to developing large electronic hematology atlases, animated, audio-enhanced learning experiences, multidisciplinary Internet conferences, and other innovative applications. Digital images of single microscopic fields (single frame images) are the most widely utilized in hematology education at this time, but single images of many adjacent microscopic fields can be stitched together to prepare "zoomable" panoramas that encompass a large part of a microscope slide and closely simulate observation through a real microscope. With further advances in computer speed and Internet streaming technology, the virtual microscope could easily replace the real microscope in pathology education. Later in this decade, interactive immersive computer experiences may completely revolutionize hematology education and make the conventional lecture and laboratory format obsolete. Patient care is enhanced by the transmission of digital images to other individuals for consultation and education, and by the inclusion of these images in patient care documents. In research laboratories, digital cameras are widely used to document experimental results and to obtain experimental data.