Analytic comparison of talc in commercially available baby powder and in pelvic tissues resected from ovarian carcinoma patients.

OBJECTIVE: Measure the size and shape of talc particles in talcum powder and compare this data to the size and shape of talc particles found in surgically resected tissues from patients with ovarian carcinoma. METHODS: Using polarized light microscopy (PLM) and scanning electron microscopy (SEM), we measured the size and shape of talc particles in samples of talc-containing baby powder (TCBP) and surgically resected pelvic tissues (hysterectomies) from talc-exposed patients with ovarian carcinoma. RESULTS: The most frequent class of particles in TCBP can be unequivocally identified as talc, using both polarized light microscopy and scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDX). The talc particles found in resected tissues from ovarian carcinoma patients are similar in size and shape to the most abundant morphological class of particles in TCBP. CONCLUSIONS: This finding, combined with previous epidemiological literature and tissue-based analytical studies, provides further evidence that the small, isodiametric particles that dominate TCBP can migrate from the perineum and become lodged in distal structures in the female reproductive tract, where they may lead to an increased risk of developing ovarian carcinoma.

Regulation of surface topography of mouse peritoneal cells. Formation of microvilli and vesiculated pits on omental mesothelial cells by serum and other proteins.

The mesothelial cells of the mouse omentum provide an in vivo model for the study of the mobilization of labile microvilli on the cell surface. These mesothelial cells are sparsely covered with microvilli and large pits 150--400 nm in diameter, termed vesiculated pits. On the unstimulated cell, the microvilli average 44/100 microns2 and pits, 30/100 microns 2 of surface and they are rapidly induced to increase in number by the intraperitoneal injection of isologous mouse serum. After 2 min, microvilli increase threefold, continue to sevenfold at 30 min, and decrease to fourfold at 90 min. Vesiculated pits increased with similar kinetics. Bovine serum albumin and gamma globulin also stimulate the microvilli and pits to form, but the response is a slow, gradual rise to five- or sixfold the normal value at 90 min. Evidence indicates that multiple factors, possibly including insulin and immunoglobulins, are involved in the effect of serum. The close physical and temporal relationship between microvilli and pits suggests that a correlation exists in their mobilization by the cell and it is hypothesized that microvilli function in the regulation of the cortical microfilament network in effecting this mobilization.

Effect of a high fat diet on quantitative features of adipocytes in the omentum: an experimental, stereological and ultrastructural study.

BACKGROUND: Omental adipose tissue specimens of female rats that were fed a high fat (HF) diet were evaluated stereologically and histopathologically. To our knowledge, there is no stereological study on numerical density, nuclear height and volume of adipocytes in omental adipose tissue in the female rat fed a HF diet in the literature. METHOD: 20 female Spraque Dawley rats were used in the study. 10 of the animals were fed HF diet consisting of 30% of calories from fat for 3 months. The remaining 10 rats, the control group, were fed a normal diet. After the experimental procedure, all animals were anesthetized and omental adipose tissues in the same area were dissected and fixed for the histochemical process using a mixture of 3% glutaraldehyde and 1% osmium tetraoxide in 0.1 M phosphate buffer. After embedding of tissues in araldite CY 212, semi-thin and thin sections were cut. The semi-thin sections were stained with toluidine blue. The physical dissector counting method was used for estimation of numerical density and nuclear height of adipocytes. Cavalieri principle was used for the estimation of adipocyte volume; volume fraction approach was applied to find the volume fraction of adipose tissue components. RESULTS: The mean numerical density of adipocytes in the HF diet group was significantly higher than the control. The mean nuclear height of adipocytes was also very high in the HF diet group. The volume fraction of adipose mass was increased whereas the extracellular matrix volume fraction was reduced in the HF diet group compared to the controls. The mean volume of adipocytes in the HF diet group was also significantly higher than in the control group. At the light microscopy level, it was found that adipocytes were enlarged and gaining irregular shape in the HF diet group. Thicker basal lamina and electron dense lipid content were also found in this group at the electron microscopy level. CONCLUSION: Lipid content and number of adipocytes in the adipose tissue of HF diet rats were higher than in the controls. Thus, HF diet induces increase in body weight via both hypertrophy and hyperplasia of adipocytes.

The Microscopic Structure of the Omentum in Healthy Dogs: The Mystery Unravelled.

The canine omentum has many valuable properties but is still an underestimated organ. It contributes in many ways to the protection of the peritoneal cavity through its versatility on immunological level, but also through its role during angiogenesis, absorption, adhesion and fat storage. Despite a wide range of applications, the basic structure of the omentum is not well documented. This study provides an insight in the microscopic structure of the canine omentum through both light microscopic and electron microscopic investigations. Two regions could be distinguished in the canine omentum: translucent and adipose-rich regions. The translucent regions were composed of two different layers: a continuous flattened mesothelium on top of a submesothelial connective tissue matrix. The adipose-rich regions consisted of a substantial layer of adipocytes on which a flattened continuous mesothelium was present. Between those two layers, a few strands of collagen fibres could be detected. Large aggregates of immune cells, the so-called milky spots, were not observed in the omentum of healthy dogs. Only a limited number of leucocytes, macrophages and neutrophils were found, scattered throughout the connective tissue in the translucent regions. At the level of the adipose-rich regions, the immunological population was virtually non-existent.

A comparative study of the structure of human and murine greater omentum.

In humans, the greater omentum is a fatty peritoneal fold that extends from the greater curvature of the stomach to cover most abdominal organs. It performs many functions, which include acting as a reservoir of resident peritoneal inflammatory cells, a storage site for lipid, and a regulator of fluid exchange in and out of the peritoneal cavity. Most importantly, the omentum readily adheres to areas of inflammation and peritoneal damage, often leading to adhesion formation. Despite its clinical importance, the omentum remains an understudied organ, and discrepancies exist as to its exact morphology. This study uses a combination of phase contrast microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) to elucidate the structure of the greater omentum of both human and mouse and determine whether it possesses a typical surface mesothelial cell lining similar to other serosa. Results indicated that both human and murine omenta were of similar structure and composed of two distinct types of tissue, one adipose-rich and the other translucent and membranous. The adipose-rich regions were well-vascularised and covered by a continuous mesothelial cell layer except at the sites of milky spots. In contrast, translucent areas were poorly vascularised and contained numerous fenestrations of varying size. The possible function and developmental origin of these gaps is unclear; however, their role in promoting omental adhesion formation and in the successful use of omental graft material is discussed.

Omentum ECM-based hydrogel as a platform for cardiac cell delivery.

Cardiovascular diseases remain the number one killer in Western countries. Despite recent advances and promising results in cardiac cell-based therapy, one of the remaining challenges is poor cell retention in the desired site. As a solution, cell delivery systems are developed to ensure that a sufficient number of viable cells reach the infarct area. These delivery systems are based on biomaterials that provide a surrogate microenvironment for the encapsulated cells, retaining them in the desired location post-delivery. Injectable thermoresponsive ECM-based hydrogels have been developed to achieve this goal. Unfortunately, the use of allogeneic or xenogeneic ECM may hamper the treatment due to an immune response to residual cellular content from the host. In this work, we have developed an omentum-based hydrogel capable of self-assembly under physiological conditions. Although in this study the omentum was obtained from porcine sources, it can be easily and safely extracted from the patient, serving as an autologous protective vehicle for the transported cells. We have characterized the biochemical composition, mechanical properties, and gelation and degradation kinetics of the processed biomaterial. Furthermore, the ability of the hydrogel to encapsulate cardiac cells and support their culture was evaluated. We envision that the newly developed platform may open new opportunities for personalized cell delivery to the heart and other tissues.

Reactive and neoplastic serosal tissue. A light-microscopic, ultrastructural, and immunocytochemical study.

Normal and reactive non-neoplastic serosal tissues and a spectrum of serosal neoplasms were studied using light-microscopic, ultrastructural, immunocytochemical, gel electrophoretic, and immunoblot techniques. Normal surface mesothelium expressed both low- and high-molecular-weight cytokeratins, whereas the scattered submesothelial cells were decorated only with antibodies to vimentin. Reactive non-neoplastic subserosal cells, however, coexpressed both low-molecular-weight cytokeratin and vimentin and demonstrated the ability for surface differentiation during which higher-molecular-weight cytokeratins were acquired and vimentin was lost. The authors suggest the term "multipotential subserosal cells," recognizing the unique intermediate filament expression of reactive subserosal cells and the ability for surface differentiation. The intermediate filament expression of the sarcomatoid/desmoplastic mesotheliomas resembled the MSC, whereas epithelial mesotheliomas resembled surface mesothelium. These findings have potential usefulness for diagnostic pathology.

Ultrastructure of the nerves in veins from human omentum.

To study the ultrastructural characteristics of the sympathetic nerve terminals of human omental veins, and of their relationship to the innervated smooth muscle cells, biopsy specimens were taken during abdominal surgery, rapidly fixed in glutaraldehyde/osmium and stained with uranylacetate. The results indicate that the veins have an extensive noradrenergic innervation, penetrating into the tunica media. The distance between nerve terminals partly or wholly free from enveloping Schwann cells, to the surface of smooth muscle cells ranged from 30 to 500 nm. Large dense core vesicles were prominent in both preterminals and terminal regions, while small dense core vesicles occurred mainly in terminals. Large dense core vesicles in close contact with the axolemma were occasionally observed, indicating involvement in secretion by exocytosis.

Ultrastructure of myofibroblasts and decidualized cells in leiomyomatosis peritonealis disseminata.

A case of leiomyomatosis peritonealis disseminata studied by light and transmission electron microscopy is reported. The lesion, from a pregnant woman, was found to contain predominantly myofibroblasts and decidualized cells in a rich collagen stroma, while relatively few leiomyocytes and fibroblasts were observed. The development and fate of this entity are discussed in view of the present findings and those previously reported.

The mechanisms of blood vessel closure in humans by the application of ultrasonic energy.

BACKGROUND: The use of the ultrasonically activated scalpel (UAS) for vessel closure has attained widespread acceptance in many surgical fields. The aim of our study was to investigate the electron microscopic changes to the blood vessels after the application of UAS. METHODS: We collected 10 arterial and 10 venous segments from vessels that had previously been closed by UAS during abdominal operations. The samples were then prepared for ultramicroscopic analysis. Pathological changes in the lumen and the three wall layers of the blood vessel were examined under scanning and transmission electron microscopy. RESULTS: All of the vessel segments showed similar changes: the presence of a blood clot, endothelial cell condensation, coagulative necrosis of the wall, and charring of the vessel at its tip. The edge of the cut vessel were closed by the coagulation bond, which was tied up by collagen fibrils escaped from denaturation. CONCLUSION: When ultrasonic energy is applied to tissues, it changes their structure so as to make a new extracellular matrix.

[Effect of activated greater omental milky spots and peritoneal macrophages on tumoricidal activity against gastric carcinoma SGC-7901 in mice].

OBJECTIVE: To investigate the effect of activated greater omental milky spots and peritoneal macrophages in mice on tumoricidal activity against gastric carcinoma SGC-7901, following intraperitoneal (i.p.) injection of INF-gamma, staphylococcin aureus or NDV-L. METHODS: The quantitative changes of milky spots were determined by activated carbon, the number of the macrophage in milky spots was assessed by nonspecific esterase stain and the number of peritoneal macrophages was counted by trypan blue exclusion. The morphology of peritoneal macrophages was observed by scanning electron microscope, the amount of TNF-alpha and iNOS mRNA expressed by peritoneal macrophages was measured by fluorescence quantitative PCR and the cytotoxicity of peritoneal macrophages supernatant against SGC-7901 was evaluated by MTT assay. RESULTS: It was found in the treated groups that: 1. The amount of greater omental milky spots and the macrophages in milky spots increased, 2. The number of peritoneal macrophages increased. The peritoneal macrophages were in activated status. The effect TNF-alpha and iNOS mRNA expression increased and 3. The cytotoxicity against in vitro SGC-7901 increased. CONCLUSION: Intraperitoneal injection of IFN-gamma, staphylococcin aureus or NDV-L could activate the milky spots of the greater omentum and the macrophages in peritoneal cavity in mice, with IFN-gamma being the best. The supernatant of activated peritoneal macrophages has cytotoxicity against SGC-7901. Administration of LPS to macrophages cultured in vitro could amplify the activation and enhance the cytotoxicity of the supernatant against SGC-7901.

[Interaction of Toxoplasma gondii endozoites with the omental cells of the white mouse in acute experimental infestation. An electron microscopic study]. / Vzaimodeistvie éndozoitov Toxoplasma gondii s kletkami sal'nika beloi myshi priostroi éksperimental'noi invazii. Elektronno-mikroskopicheskoe issledovanie.

The omentum of 8 white mice was examined 24--96 hours after the intraperitoneal infection. Endozoites are capable of intensive intrusion not only into phagocytizing cells (hystocytes, peritoneal macrophages) but also into the cells which are not phagocytes (mesothelium). Just after the intrusion metabolism of the host-cell intensifies and in it are formed special structures which facilitate metabolic processes between the cell and the parasite (microvilli on the membrane of the parasitophore vacuole). At the final stage of the interaction with the cell endozoites cause the lysis of the membrane of the parasitophore vacuole that facilitates their transition into new cells. The ability to intrude into the cells, which are not phagocytes, and to cause the lysis of parasitophores vacuole is a factor of pathogenicity of virulent strains of toxoplasms which determines the generalized character of the infection caused by them.

[Morphogenic role of the underlying substrate of endothelial and mesothelial cells]. / O formogennoí roli podlezhashchego substrata éndotelial'nykh i mezotelial'nykh kletok.

Endothelial and mesothelial cell form, cell surface microrelief and intercellular contacts were studied by scanning electron microscopy. The pattern of the underlying substrate (geometry and expressiveness of basal membrane) is shown to influence the endothelial and mesothelial cell morphology. The morphogenic role of the underlying substrate is discussed.

[Histogenesis of the omental milk spot of the mouse (author's transl)].

The mouse omental milk spots can be classified into two types, type I and II. The type I spots are seen in the margin of the fatty tissue along the omental vessels, and the type II spots are scattered on the omental peritoneum. In this study, histogenesis of the two types of milk spots was examined with the light and electron microscope. 1. Milk spots are not yet observed at birth, but macrophages are already intermingled with mesenchymal cells along the omental vessels and within the omental peritoneum. 2. Fat cells first appear along the omental vessels at 1 to 2 days of age and they then form fatty tissue at 3 to 5 days. Mononuclear cells such as lymphocytes, lymphoid cells and macrophages are scattered within the fatty tissue. At 6 to 10 days capillary network is developed along the margin of the fatty tissue, and lymphocytes, lymphoid cells and macrophages are accumulated along capillaries. Thus type I milk spots are formed. Lymphocytes and lymphoid cells are frequently seen also within the capillary lumens. They are sometimes seen crossing the capillary walls. Macrophages in the deeper zone of milk spots are generally small, but macrophages in the superficial zone are large and well differentiated in appearance. 3. The proportions of constituent cells in type I milk spots were examined at various ages. In spots in early life, macrophages, lymphoid cells and lymphocytes are relatively few, occupying 7 to 8% in proportion, respectively. Then lymphocytes increase in number with age, and they are more than 50% after 1 month of age. Lymphoid cells remain almost unchanged in proportion, being 7 to 11%. Macrophages constitute 2 to 3% after 1 month. 4. Type II milk spots appear later than type I spots, and they are first seen at 12 days of age, especially on the dorsal layer of the omentum. They then increase in number with age. 5. Functional significance of the milk spots was discussed in relation to their histogenesis.

[Morphological studies of the omental milk spots in the mouse: light and electron microscopy (author's transl)].

In adult dd-mice of both sexes ranging in age from 2 to 8 months, the omental milk spots were studied by light and electron microscopy. 1. Omental milk spots could morphologically be classified into two types, namely, type I and type II. 2. Type I spots were seen on the margin of the fatty tissue along the omental artery and vein. This type of spots were supplied with capillary vessels. 3. Type II were scattered on the omental peritoneum, particularly in abundance on the dorsal layer of the omentum. The spots of this type generally had no vascular supply. Type II milk spots on the dorsal layer were significantly more numerous in females than in males. 4. The two types of milk spots were composed mainly of macrophages, lymphoid cells and lymphocytes, although the constituents were different in proportion between the two types. The type I spots had abundant macrophages especially in the superficial zone. Lymphoid cells and lymphocytes were relatively abundant in the deeper zones. The type II were also abundant in macrophages which were scattered diffusely in the spots. 5. Macrophages had slightly PAS positive cytoplasm which contained PAS positive granules and vacuoles. Macrophages in the superficial zone of the spot were large with abundant lysosomes and vacuoles. Lymphoid cells were more or less similar in appearance to lymphocytes, but their cytoplasm was more abundant than that of lymphocytes, and had lysosomes and bundles of microfilaments. In addition, large macrophages were also distributed diffusely within the fatty tissue along the omental vessels and between the opposed peritoneium of the omentum. They had abundant light cytoplasm with numerous projections on the surface. The organelles were generally well developed. The cytoplasm had abundant lysosomes, coated vesicles and small tubules. Lymphocytes were generally small lymphocytes. 6. The endothelial cells of capillaries in type I spots were fenestrated. 7. The functional significance of the two types of spots was discussed on the basis of the structure.

[Uptake of horseradish peroxidase (HRP) in omental milk spot cells of the mouse: an electron microscope study (author's transl)].

In adult dd-mice horseradish peroxidase (HRP) was injected intraperitoneally, and the response of omental milk spot cells was systematically observed by electron microscopy. In the omental milk spots, macrophages were very active in uptake of HRP. However, the activity was different between macrophages which existed in the superficial zone of milk spots and those which were seen in the deeper zone and the fatty tissue deep to the milk spots. Thus the two types of macrophages could be distinguished not only by structural details but also by uptake response to HRP. Lymphoid cells in the spots could take up very small amounts of HRP just after HRP injection, whereas lymphocytes showed no HRP uptake. Mesothelial cells and fibrocytes could take up small amounts of HRP.

[Response of omental milk spots to colloidal saccharated ferric oxide in the mouse: light and electron microscopic study (author's transl)].

In adult dd-mice, response of omental milk spots to colloidal saccharated ferric oxide intraperitoneally injected was observed by light and electron microscopy. Macrophages in milk spots and the fat tissue along the omental vessels took up large amounts of iron particles 1 hr after injection. Lymphoid cells in milk spots also could take up iron particles, though in very small amounts. At 2 hrs, milk spots were obscure in structure owing to remarkable infiltration of granulocytes. At 12 hrs, mononuclear cells appeared to be accumulated around blood vessels in the superficial zone of the fat tissue. Thus new milk spots appeared to be formed again. At 1 day, macrophages started to appear within formed milk spots. These cells had the ability to take up iron particles, and histochemically showed acid phosphatase activity. In addition, they were accumulated in thick layers along the surface of the fat tissue and milk spots 4 days after injection, but they then became gradually less in density with advancing time. Macrophages in the fat tissue, which could be distinguished from the ones in milk spots by remarkable HRP uptake, disappeared during the first 12 hrs after injection, but they appeared again along vessels in the fat tissue 1 day after injection. The response of two types of macrophages in omentum to colloidal iron was particularly discussed in detail.

Scanning electron microscopic study for pore formation of the greater omentum of cats.

The greater omentum of the cats is said to have a lace-like structure. However, there are only a few descriptions on whether pores exist, and there are not many morphological studies on this meshwork. In this study, the greater omentum of the cats was observed at each age of development using a scanning electron microscope. The greater omentum of the cats immediately after birth was found to be continuous, and no pores were observed. Also, development of microvilli was observed in the mesothelial cells on the surface of the greater omentum. In young cats at 3 months of age, small pores were sporadically observed, and at the ages of 6-12 months, there were more and larger pores. It was estimated that the pores on the greater omentum are formed in the process of moving from the movement of organs, such as the stomach, intestines and diaphragm, and the presence of these pores enables the passage of ascites between the omental bursa, the greater omentum and the serosal cavity of the wall without flowing through the omental foramen.