Low Magnification Light Microscopy Research Articles

Three-dimensional microanatomy of human nipple visualized by X-ray dark-field computed tomography.

The three-dimensional (3D) structure of the human nipple has not been fully clarified. However, its importance has increased in recent years because it has become common practice to preoperatively explore the spread of breast cancer to the nipple with needle biopsy, ductoscopy, and/or ductal lavage for nipple-sparing mastectomy. Here, we demonstrated that X-ray dark-field computed tomography (XDFI-CT) is a powerful tool for reconstructing the 3D distribution pattern of human lactiferous ducts non-destructively, without contrast agent, and with high tissue contrast. Nipples amputated from mastectomy specimens of 51 patients with breast cancer were visualized three-dimensionally by XDFI-CT. First, CT images and conventionally stained tissue sections were compared to demonstrate that XDFI-CT provides 3D anatomical information. Next, the number of ducts in the nipple and the number of ducts sharing an ostium near the tip of the nipple were measured from the volume set of XDFI-CT. Finally, the 3D distribution pattern of the ducts was determined. XDFI-CT can provide images almost equivalent to those of low-magnification light microscopy of conventional hematoxylin-eosin-stained histological sections. The mean number of ducts in all cases was 28.0. The total number of ducts sharing an ostium near the tip of the nipple was 525 of 1428. The 3D distribution patterns of the ducts were classified into three types that we defined as convergent (22%), straight (39%), or divergent (39%). XDFI-CT is useful for exploring the microanatomy of the human nipple and might be used for non-invasive nipple diagnosis in the future.

Mechanical Behavior and Failure Analysis of Prosthetic Retaining Screws after Long‐term Use in vivo. Part 4: Failure Analysis of 10 Fractured Retaining Screws Retrieved from Three Patients

The aim of this study was to perform a failure analysis on fractured prosthetic retaining screws after long-term use in vivo. Additionally, the study addresses the commonly asked question regarding whether complex repeated functional occlusal forces initiate fatigue-type cracks in prosthetic retaining screws. Ten fractured prosthetic retaining screws retrieved from three patients treated with fixed detachable hybrid prostheses were subjected to a failure analysis. In patients 1 and 2, the middle three retaining screws of the prostheses were found fractured at retrieval time after they had been in service for 20 and 19 months, respectively. In patient 3, the middle three and one of the posterior retaining screws were found to be fractured at retrieval after they had been in service for 18 months. Low power stereomicroscopy and high-power scanning electron microscopy (SEM) were performed to analyze the fractured surfaces of the retaining screws examining fatigue cracks in greater detail. Typical fatigue failure characterized by ratchet mark formation was revealed by light microscopy and SEM for all examined screws. Using low magnification light microscopy, ratchet marks were visible on the fracture surfaces of only two screws. SEM examination revealed all three classical stages of fatigue failure, and it was possible to see the ratchet marks on the fracture surfaces of all specimens, indicating a fatigue zone. The final catastrophic overload fracture appeared fibrous, indicating ductile fracture. The final overload ductile fracture surfaces showed equiaxed dimples, suggesting tensile overload in all examined screws except in two specimens that showed an elongated dimple pattern indicating shear/tearing overload forces. Fracture of prosthetic retaining screws in hybrid prostheses occurs mainly through a typical fatigue mode involving mostly the middle anterior three screws. Fatigue cracks can grow in more than one prosthetic retaining screw, leading to fracture before the patient or clinician determines that any problem exists.

Dental microwear variation in complete molars of Loxodonta africana and Elephas maximus

Dental microwear analysis is an important addition to the field of paleoecology, and has proven useful for inferring dietary preferences in extant and extinct species. New techniques involving the use of low-magnification light microscopy have become very popular for use with large specimens that pose logistical problems for analysis with traditional scanning electron microscopy. In this study, the dental microwear of two complete molars from the extant elephants, Loxodonta africana and Elephas maximus was examined using low magnification light microscopy. The African elephant molar had a higher percentage of scratches versus pits when compared to the Asian elephant. Previous studies on elephant teeth have examined only a sample area of each lamella, and based on this study, much variation is present within a single molar from anterior to posterior lamellae as well from buccal to lingual sides of these plates, and so analysis of a sample area of enamel may not be providing consistent information on diet preference.

Observer‐independent analysis of high‐resolution MR images of the human cerebral cortex: In vivo delineation of cortical areas

Using high-resolution MRI, it is now possible to examine the living human cortex down to a resolution of less than 300 mum. Thus, in vivo imaging is now approaching the resolution that has been successfully used in histological analysis of the cerebral cortex for many years, e.g., low-magnification light microscopy. This allows unprecedented views of cortical microstructure that reflect defined histological features, specifically, individual cortical layers. As in histological brain mapping, it is possible to use the changes in the cortical lamination patterns to define individual cortical areas. This allows in vivo neuroanatomical maps to be generated for individual subjects and precise correlation of the results from functional imaging studies in these subjects with their own microanatomical information. To this end, we adapted the well-established observer-independent cytoarchitectonic mapping techniques for defining cortical borders based on changes in cortical lamination for in vivo parcellation of high-resolution structural MR images.

Sonographic Appearance of Nodular Fasciitis

First described in 1955, nodular fasciitis, or pseudosarcomatous fibromatosis, is a benign, self-limiting reactive process composed of proliferating fibroblasts in a myxoid stroma. 1 - 6 A rich cellular array of spindle-shaped fibroblasts, micro-hemorrhages, and numerous mitotic figures are characteristic features on low-magnification light microscopy. 3 Nodular fasciitis most commonly appears in the third and fourth decades with a solitary, rapidly growing, sometimes painful nodule arising in the upper extremity,4-6 which can be clinically confused with a sarcoma. Although a relatively common lesion, nodular fasciitis is underreported in the radiology literature. Typical magnetic resonance imaging (MRI) findings include low signal intensity on Tl-weighted images and high signal intensity on T2-weighted images, although they vary in homogeneity and patterns of enhancement. 4 , 5 On sonography, nodular fasciitis has been described as oval or lobulated, isoechoic, or with mixed areas of isoechogenicity and hypoechogenicity 7 As described below, we report a case of a patient with nodular fasciitis who underwent extensive imaging including sonography and MRI and describe the imaging features of this disease process. In this case, the lesion was well defined and slightly hypoechoic yet mildly heterogeneous and showed posterior acoustic enhancement.

Macromastia: how much of it is fat?

A total of 25 patients who underwent bilateral breast reduction were included in this study. Each patient's age, weight, height, and amount of breast tissue removed from each breast were recorded. The body mass index was calculated for each patient. On the day of the operation, tissue samples (two each) were taken from the central, lateral, and preaxillary areas of the breast. One of the samples was weighed, placed in a closed glass container, and heated for 10 minutes in a microwave oven at full power. The liquid fat was separated from the solid residue, and the percentage of fat was calculated. The other sample from each area was examined grossly, and representative sections, corresponding to the distribution of fat and connective tissue, were submitted for evaluation. In these samples, the percentage of fat, gland, and connective tissue was estimated using low-magnification light microscopy. In this group of patients (who had an average age of 34 years and who were significantly overweight as determined by a mean body mass index of 28), it was found (using the microwave method) that there was a mean fat percentage of 61 percent in the central breast area, 74 percent in the lateral breast area, and 73 percent in the preaxillary area. Upon microscopic examination, the pathologist reported that fat accounted for 64 percent of the central breast area, 92 percent of the lateral breast area, and 94 percent of the preaxillary area. On average, the central breast area in macromastia patients had only seven percent gland and 29 percent connective tissue. The lateral and preaxillary areas of the breast had one to three percent gland and five percent connective tissue. The two methods had a significant (p < 0.05) positive correlation in the central breast area, but in the lateral and preaxillary regions, the correlation was poor. In the microscopic examination, there was a tendency to overestimate the amount of fat. Both methods of evaluation used in the study concur that the enlarged breast of macromastia consists primarily of fat and that the glandular element is rather small.

Method for quantitative analysis of glycosaminoglycan distribution in cultured natural and engineered cartilage.

Cartilage tissue engineering can provide a valuable tool for controlled studies of tissue development. As an example, analysis of the spatial distribution of glycosaminoglycans (GAG) in sections of cartilaginous tissues engineered under different culture conditions could be used to correlate the effects of environmental factors with the structure of the regenerated tissue. In this paper we describe a computer-based technique for quantitative analysis of safranin-O stained histological sections, using low magnification light microscopy images. We identified a parameter to quantify the intensity of red color in the sections, which in turn was proportional to the biochemically determined wet weight fraction of GAG in corresponding tissue samples, and to describe the spatial distribution of GAG as a function of depth from the section edge. A broken line regression model was then used to determine the thickness of an external region, with lower GAG fractions, and the spatial rate of change in GAG content. The method was applied to the quantitation of GAG distribution in samples of natural and engineered cartilage, cultured for 6 weeks in three different vessels: static flasks, mixed flasks, and rotating bioreactors.

Detection of gravity-induced polarity of cytoplasmic streaming in Chara.

Gravity induces a polarity of cytoplasmic streaming in vertically-oriented internodal cells of characean algae. The motive force that powers cytoplasmic streaming is generated at the ectoplasmic/endoplasmic interface. The velocity of streaming, which is about 100 micrometers/s at this interface, decreases with distance from the interface on either side of the cell to 0 micrometers/s near the middle. Therefore, when discussing streaming velocity it is necessary to specify the tangential plane through the cell in which streaming is being measured. This is easily done with a moderate resolution light microscope (which has a lateral resolution of 0.6 micrometers and a depth of field of 1.4 micrometers), but is obscured when using any low resolution technique, such as low magnification light microscopy or laser Doppler spectroscopy. In addition, the effect of gravity on the polarity of cytoplasmic streaming declines with increasing physiological age of isolated cells. Using a classical mechanical analysis, we show that the effect of gravity on the polarity of cytoplasmic streaming cannot result from the effect of gravity acting directly on individual cytoplasmic particles. We suggest that gravity may best be perceived by the entire cell at the plasma membrane-extracellular matrix junction.

The morphology and physiology of a "mini-ommatidium" in the median optic nerve of Limulus polyphemus.

Examination of the Limulus median optic nerve with low-magnification light microscopy allows clear visualization of an ultraviolet-sensitive mini-ommatidium enshrouded by pigment cells, glial cells, and guanophores. Serial 1-micron sections of median optic nerves containing mini-ommatidia revealed the presence of a single, heavily pigmented photoreceptor (retinular) cell and a single, unpigmented arhabdomeric cell. Computer-assisted serial reconstructions from 1-micron sections confirmed the presence of two cells, each bearing a nucleus, and two axons leaving the mini-ommatidium. The retinular cell is morphologically similar to retinular cells from the median and lateral eyes. Its rhabdomere appears to be a continuous sheet of microvilli with much infolding. The structure of the arhabdomeric cell is nearly identical to those found in the median ocellus. As in other photoreceptors in Limulus, the retinular cell of the mini-ommatidium is innervated by efferent fibers from the brain. Each mini-ommatidium generates a single train of nerve impulses in response to light, presumably from the arhabdomeric cell. Measurement of the spectral sensitivity of the mini-ommatidium based upon a constant-response criterion indicated that the retinular cell is maximally sensitive to near ultraviolet light with lambda max = 380 nm. Comparison of intensity-response functions revealed that those of the mini-ommatidium are significantly steeper than those of the ocellus almost certainly as the result of neural processing in the ocellus which is absent in the mini-ommatidium.

Nurse cells of the bursa of Fabricius: Do they exist?

Cell-cell interactions in B lymphocyte development have so far been incompletely characterized, mostly due to lack of a special organ for B cell maturation in the mammalian species. Certain well-known lymphostromal interactions in the thymus have raised the question whether similar interactions with nurse cells would also operate in the development of B cells. We have tested this hypothesis in the chicken bursa of Fabricius, an organ specific for the B cell maturation. To identify possible nurse cells, with viable lymphocytes enclosed, the cells in the bursa of Fabricius were dispersed with collagenase and trypsin. Light and electron microscopic examination of bursa cell suspensions showed four types of aggregates, identified by low magnification light microscopy as potential nurse cell-like complexes. Electron microscopy revealed that all aggregates consisted of epithelial cells, and complexes of epithelial cells with lymphocytes enclosed were not observed. These findings indicate that interactions similar to those seen in the avian and mammalian thymus between epithelial nurse cells and T lymphocytes are not a part of the avian B cell differentiation process.

Electron Microscopy of Sarcocystis fusiformis

Thin sections of cysts of Sarcocystis fusiformis were studied in situ in the myocardium. Cysts were enclosed by a cyst wall. The external boundary of the cyst wall consisted of alternating long and short villous-like projections. Some long villi were seen within vacuoles in the surrounding myocardial cells. The basal portion of the cyst layer contained interwoven fibrils. The cells of S. fusiformis contained three regions. The anterior third contained sarconemes which seemed to originate in the conoid. The middle zone contained mitochondria and many bodies of various sizes, shapes, and electron density. The posterior portion of the cell contained a prominent nucleus, osmophilic bodies, and mitochondria. Spindle-shaped cysts are frequently seen in histologic sections of the myocardium of normal cattle. These cysts are referred to as Miescher's tubules and are readily discernible by low magnification light microscopy. Rounded cells in cysts have been designated as trophoblasts and banana-shaped cells as trophozoites (Levine, 1961). However, the fine cellular detail of sarcosporidial cells within cysts is not revealed by light microscopy, even though the presence of a nucleus has been resolved by the Feulgen reaction (Breindl and Komarck, 1928). Recently the electron microscope has been used to determine the fine structure of Sarcocystis tenella (see Ludvik, 1958; Senaud and de Puytorac, 1961, 1962) and S. miescheriana (see Ludvik, 1960), the agents of sarcosporidiosis in sheep and pigs, respectively. The ultrastructural morphology of Sarcocystis of bovine origin, S. fusiformis (species presumed on the basis of host in which it was found), is described in this paper. Previous publications of the ultrastructure of Sarcocystis have used fresh material obtained from the musculature of infected animals whereas in this study the cysts of Sarcocystis were examined in infected musculature in situ. MATERIALS AND METHODS Small pieces of myocardium from the left ventricle were obtained from beef animals at a local packinghouse. The tissues were fixed in 4% glutaraldehyde in pH 7.3 Sorenson's buffer (Sabatini et al., 1963). Each sample of myocardial tissue Received for publication 20 December 1965. * This study was supported in part by a grant (H-6580) from the NIH, U. S. Public Health Service. t Florida Agricultural Experiment Stations Journal Series 2273. was cut into two sections. One portion was embedded in paraffin, cut at 5 ,u, stained with hematoxylin-eosin, and examined for Sarcocystis with the light microscope. When parasites were found in histologic sections, the corresponding area of the second portion of myocardium was prepared for electron microscopy. Glutaraldehyde-fixed musculature was washed in Sorenson's buffer, postfixed in 1%o OsO (Caulfield, 1957), and embedded in Araldite (Luft, 1961). Thin sections on grids, following staining with lead, uranyl acetate, or a combination of the two metals, were examined with a Philips EM200 electron microscope.