The superior horizontal pancreatic artery of Popova: a review and an anatomoradiological study of an important morphological variant of the pancreatica magna artery.

PURPOSE: The superior horizontal pancreatic artery was described in 1910, and after a few years, it was forgot by most investigators. This research is aimed to revive the description of this artery, describing course, pattern of branching and frequency. METHODS: More than 1,000 of angiographies including studies of the superior mesenteric artery, celiac trunk and its branches, were selected from the angiographic archives of the ex-institutes of Radiology of Siena, Rome (University of Sacro Cuore) and Perugia, and the arterial anatomy of the pancreas was studied. RESULTS: A pancreatic branch of the splenic artery running along the superior border of the pancreatic body and tail was observed in 25.93% of cases. This branch matched the description of the superior horizontal pancreatic artery and, when existing, replaced the pancreatica magna artery. For this reason, we considered the superior horizontal pancreatic artery as a variant of the pancreatica magna artery. Variable in caliber and importance, in most cases the superior horizontal pancreatic artery gave off descending branches that anastomosed with the inferior pancreatic artery. CONCLUSIONS: A superior horizontal pancreatic artery could be visualized more easily by selective angiography of the splenic artery. When coupled with the inferior pancreatic artery, the presence of the superior horizontal pancreatic artery outlined a longitudinally arranged pattern of blood supply of the distal pancreas that should be known. In particular circumstances, extended resections of the gland cutting both longitudinal arteries might jeopardize the surviving of the pancreas remnant.

Nestin expression in normal adrenal gland and adrenocortical tumors.

Human adrenocortical cells have been shown to express cytokeratins and vimentin. Nestin is an intermediate filament protein that is mainly expressed in the developing nervous system and that has been recently reported in rat adrenal gland as well. Using immunohistochemical and biochemical approaches, the present study demonstrates that nestin is constantly expressed in situ in the cortex of normal human adrenal glands. Nestin expressing cells were prevalently located in the zona reticularis but some positive cells could be spotted in the zona fasciculata as well. Moreover, patches of nestin-positive cells have been constantly detected on sections of cortical adenomas. In contrast, adrenal carcinomas displayed a variable number of nestin-immunoreactive cells that in some cases were virtually absent. Samples of renal clear cell carcinoma metastasis in the adrenals were also examined which did not show nestin-immunoreactivity. We propose that a positive nestin-immunoreaction could be useful in differential diagnosis of clear cell tumors in adrenal glands.

Angiotensinogen localization and secretion in the rat pancreas.

Renin and angiotensinogen have been previously found in the rat pancreas, and angiotensin receptors have been located in the apical domain of duct cells. To evaluate the possibility that angiotensin II could be generated within the duct system, we decided to determine whether angiotensinogen is present in rat pancreatic juice and the angiotensinogen-immunoreactive pancreatic cell types that could be responsible for its production. Angiotensinogen was detected in significant amounts by Western blotting in pancreatic juice collected from several individual rats. Different isoforms between plasma and pancreatic juice angiotensinogens were demonstrated by isoelectric focusing. Immunocytochemical experiments revealed angiotensinogen-immunoreactive cells at the periphery of the islets of Langerhans, and confocal microscopy demonstrated that most angiotensinogen-immunoreactive cells were glucagon-secreting cells. Secretion of angiotensinogen did not follow the regulated secretory pathway since it was absent from the glucagon-containing granules. This was confirmed by electron microscopy immunocytochemistry. Duct and acinar cells did not express angiotensinogen at an immunocytochemical detectable level. The present findings indicated an exocrine secretion of angiotensinogen by glucagon-secreting cells and suggest that one of the final targets of the local pancreatic renin-angiotensin system may be the duct epithelium.

Association between islets of Langerhans and pancreatic ductal system in adult rat. Where endocrine and exocrine meet together?

AIMS/HYPOTHESIS: Studies on the functional and morphological relations between exocrine and endocrine pancreas have been conducted mainly to disclose the influence of islets of Langerhans on acinar parenchyma. Less attention has been paid to the relations occurring between islets and pancreatic ducts. METHODS: A series of consecutive sections of normal adult rat pancreas were double stained with islet (hormones) and duct (cytokeratin 20) markers. Electron microscopy was conducted to investigate the ultra-structural features of duct-islet relations and anti-insulin immunogold labelling was carried out to reveal the presence of insulin in the pancreatic duct system. RESULTS: Consecutive double-stained sections demonstrated that 73.60 +/- 2.97% of the islets were attached to the ducts. For each series, 93.48 +/- 5.43 % of the islets contacting the duct tree were associated with small-sized ducts or centroacinar cells. Electron microscopy revealed that some insulin and somatostatin cells do face the duct lumen. Insulin was detected within the duct lumen and in the endosomal compartment of the duct cells. CONCLUSIONS/INTERPRETATION: The finding that most islets are connected with the duct system in the adult pancreas is discussed in terms of hormone secretion into the ducts, islet histogenesis and the relation among the three tissue components of the pancreas, the endocrine, the exocrine and the duct system.

Pancreatic lymphatic system in rodents.

The lymphatic network of the pancreas has been little investigated and recent studies have provided contrasting data. This research is aimed to supply the morphologic basis to outline the involvement of the lymphatic system in pancreatic pathology. Guinea pigs, rats, and mice were anesthetized with ether and sacrificed with the same anesthetic. Pieces of pancreas were processed for transmission electron microscopy. Semithin sections were observed by light microscopy and, after positive identification by transmission electron microscopy, lymphatics were followed with long series of consecutive sections to define their distribution. Lymphatics were detected in the pancreas of all the animals both in the inter and the intralobular sites. Closer relations with the exocrine parenchyma (ducts and acini) were observed in guinea pig pancreas. Remarkably, interesting relationships between lymphatics and endocrine tissue were observed in all the animals. Overall, however, the lymphatic network of rat pancreas was less develop and preferentially associated with blood vessels. The distribution of the pancreatic lymphatic network appears consistent with an active role in pancreatic pathology.

GFAP is expressed as a major soluble pool associated with glucagon secretory granules in A-cells of mouse pancreas.

To elucidate the role of intermediate filament proteins in endocrine cells, we investigated the expression and subcellular distribution of GFAP in mouse islets of Langerhans. For this purpose, combined immunocytochemical and biochemical analysis with a panel of antibodies was carried out to identify GFAP-immunoreactive cells in mouse endocrine pancreas. Cell fractionation into NP-40-soluble and detergent/high salt-insoluble components was performed to assess whether GFAP was located in the cytosolic and/or cytoskeletal compartments of immunoreactive cells. Immunoelectron microscopic analysis was carried out to determine the subcellular distribution of the protein. Peripheral islet cells were stained with anti-GFAP antiserum. These cells were identified as glucagon-secreting cells by immunocytochemical staining of consecutive sections with anti-somatostatin, anti-GFAP, and anti-glucagon antisera. Western blotting analysis of both NP-40-soluble and detergent/high-salt insoluble fractions of isolated islets of Langerhans allowed detection of GFAP in both cytosolic and cytoskeletal compartments. Interestingly, however, the former location was highly predominant. In addition, immunoelectron microscopy localized GFAP associated with the periphery of secretory granules. On the basis of these results, an intriguing role for GFAP in secretory events should be strongly suspected.(J Histochem Cytochem 48:1233-1242, 2000)

Glial fibrillary acidic protein (GFAP)-like immunoreactivity in rat endocrine pancreas.

The study of intermediate filament expression in the pancreatic epithelium has been previously focused almost exclusively on cytokeratins. Transient vimentin immunoreactivity has also been detected in duct cells of rat fetal pancreas. Here we report that, in rat pancreas, intense GFAP-like immunoreactivity is detectable in a subpopulation of endocrine cells located in the periphery of the islet of Langerhans. In addition, staining appeared to be preferentially localized to the apical pole of the cells. Two different polyclonal antibodies were employed in this study, with analogous results. Staining of consecutive sections with anti-GFAP, anti-glucagon, and anti-somatostatin antibodies demonstrates that GFAP-like immunoreactivity is present in glucagon-secreting cells. The relevance of this finding is discussed. (J Histochem Cytochem 48:259-265, 2000)

Expression of beta1 integrins in glomerular tissue of Streptozotocin-induced diabetic rats.

Based upon the importance of integrins as receptors for extracellular matrix components as well as transducers of extracellular signals, and since major alterations take place in the renal extracellular matrix during diabetes, it is important to study the role played by integrins in the development of the diabetic glomerulosclerosis. Expression of the beta1 subunit by renal glomerular cells was evaluated by biochemical and morphological means in short- and long-term diabetic rats. Western blots of isolated rat renal glomeruli demonstrated that the expression of beta1 increases along with age as well as with the hyperglycaemic state. These changes were significant as early as 6 weeks of hyperglycaemia. This was further demonstrated by immunocytochemistry, which revealed the presence of the beta1 subunit at the level of the plasma membranes of endothelial, epithelial, and mesangial cells. Quantitation of the immunolabelings confirmed the increased expression of beta1 under diabetic conditions. Further to this, expression of the focal adhesion kinase (FAK) was evaluated by immunoblotting showing little increase in diabetic conditions. On the other hand, testing the tyrosine phosphorylation of FAK, revealed significant increases in diabetes. To recover the fraction of FAK associated with the beta1 subunit, immunoprecipitation of isolated glomeruli homogenates was carried out with the anti-beta1 antibody. This demonstrated that the amounts of FAK co-precipitated with beta1, as well as its tyrosine-phosphorylation, are in fact reduced in diabetic conditions. Since the changes reported were observed at time points prior to any morphological alteration of the renal extracellular matrix, it appears that modifications in integrins and in their intracellular relays constitute early events that precede the onset of the diabetic nephropathy and must then be associated with the hyperglycaemic condition.

Type VI collagen in glomeruli of short- and long-term experimental diabetic rats.

Type VI collagen was revealed by high-resolution immunocytochemistry in renal glomeruli from short- and long-term streptozotocin-injected hyperglycaemic rats and from their age-matched normoglycaemic controls. The labellings obtained over the glomerular basement membrane and the mesangial matrix were assessed by quantitative evaluations. The labellings over the glomerular basement membrane were low and sparse in the young normoglycaemic animals but became consistent and increased in intensity with age and in both the short- and long-term diabetic animals. For the mesangial matrix, this was labelled more systematically, and its intensity increased with age and in the short-term hyperglycaemic animals. For the long-term hyperglycaemic animals, the intensities of labelling resembled those of their age-matched controls. These results indicate that type VI collagen appears to be a minor constituent of the extracellular matrix of the rat glomeruli, rather concentrated in the mesangial area in the young control animal. Concomitant with the general modifications of the extracellular matrix occurring with age and diabetes, this component increases, but apparently not with the length of the hyperglycaemic state.

Alterations in the expression of the alpha 3 beta 1 integrin in certain membrane domains of the glomerular epithelial cells (podocytes) in diabetes mellitus.

In view of the major alterations which take place at the level of the extracellular matrix of the glomerular wall in diabetes mellitus and the key roles played by beta 1 integrins in cell-to-matrix interactions, it is imperative to understand the role played by integrins in the development of diabetic glomerulosclerosis. In the present study, we revealed by immunocytochemistry the ultrastructural distribution of the alpha 3 beta 1 at the level of the plasma membrane of the different renal glomerular cells from short- and long-term diabetic rats. For the endothelial cells, the labelling present on both the luminal and abluminal plasma membranes was low. For the podocyte epithelial cells, the labelling was present on both the luminal and basal plasma membranes, the former being concentrated at points of contact between podocyte foot processes. The labelling on the basal plasma membrane was more significant and similar in domains facing either the glomerular basement membrane or the mesangial matrix. The plasma membrane of mesangial cells also exhibited alpha 3 beta 1. The labelling was recorded under diabetic conditions, at the same sites, with similar intensities, alongside that of the basal plasma membrane of podocytes facing the glomerular basement membrane, the density of which decreased significantly. This decrease in labelling was similar in renal tissues from short- and long-term diabetic animals. These results demonstrate that alpha 3 beta 1 present at the podocyte basal plasma membrane facing the glomerular basement membrane, which undergoes important alterations in diabetes, could be involved in the major dysfunctions of the glomerular wall characteristic of diabetic glomerulosclerosis. Since the changes in integrin were found to occur as early as after 1 month of hyperglycaemia, when morphological alterations of the glomerular basement membrane are not yet established, we propose that they constitute an early event which precedes the onset of diabetic nephropathy.

Modifications of the follicle-associated epithelium by short-term exposure to a non-intestinal bacterium.

This study was undertaken in order to study the effects of short-term exposure of the follicle-associated epithelium (FAE) of rabbit Peyer's patches to a non-intestinal, Gram-positive bacterium. Isolated ileal loops, each containing one Peyer's patch (PP), were stimulated for short periods of time (30 and 60 min) with Streptococcus pneumoniae R36a, a micro-organism normally not present in the intestinal area. Samples from antigen-stimulated and control Peyer's patches were analysed by light (LM), transmission electron (TEM), and scanning electron microscopy (SEM). Stimulation with living pneumococci induced dramatic changes in FAE architecture and morphology. A massive passage of cells from lymphoid tissue to the FAE was rapidly detectable, accompanied by alterations of the FAE surface, with a marked increase of M-cell area. Furthermore, TEM analysis revealed that M cells were able to internalize living pneumococci. S. pneumoniae R36a is a valid experimental model for the further study of the unique antigen sampling function which characterizes the highly specialized FAE in Peyer's patches.

Development of the role-play inventory of situations and coping strategies for parents of children with cystic fibrosis.

Critiqued previous conceptual and methodological approaches to the measurement of stress and coping. Applied Goldfried and D'Zurilla's behavior-analytic model to create a context-specific measure of problematic situations and coping strategies for parents of school-age children with cystic fibrosis (CF). The sample was stratified by child's gender and illness severity. Forty-seven families (46 mothers, 32 fathers) and 8 health care professionals completed structured interviews or daily diaries to obtain the widest range of problematic situations; 1,725 situations were elicited across all participants and then content-analyzed into 97 nonredundant categories in 11 domains (e.g., Discipline, Medical Care). Few differences were found in problem frequency or difficulty as a function of either gender or illness severity. Using empirical criteria, the most frequent and difficult problem situations were selected and developed into role-play vignettes that include relevant contextual, developmental, and interactional details. The Role-Play Inventory of Situations and Coping Strategies (RISCS) consists of 31 audiotaped vignettes designed to elicit and evaluate the coping strategies used by parents of children with CF.

Three-dimensional (3D-) reconstruction of M cells in rabbit Peyer's patches: definition of the intraepithelial compartment of the follicle-associated epithelium.

One of the major cell components of the rabbit follicle-associated epithelium is represented by the M cells. M cells are able to harbour variable amounts of immunocompetent cells inside peculiar invaginations of their basolateral cytoplasmic membrane, currently referred to as "pockets." This study provides a description of the exact spatial relationships between the M cells and the cells harboured in these so-called "pockets." Pieces of Peyer's patches, taken from the small intestine of an adult male rabbit, were treated as usual for conventional electron microscopy. Consecutive semithin and ultrathin sections were made through the entire thickness of the follicle-associated epithelium along planes parallel to the mucosal surface. Micrographs, taken from the ultrathin sections, were transposed into a software MacDraw Pro to obtain a computerized three-dimensional reconstruction. Three-dimensional reconstruction of the M cells showed that the "pockets" were not formed by mere invaginations of the cytoplasmic membrane, but that they resulted from the branching of the supranuclear portion of the M cell cytoplasm around the M cell-infiltrating lymphocytes. These intrusive cells could be found inside the "pockets" or lined up with one another, in vertical columns, bordering on the basal aspect of the M cells. The particular arrangement of the M cell apical cytoplasm created a labyrinth within the follicle-associated epithelium, which could be assumed as a real intraepithelial compartment expandable virtually throughout all the epithelium. The functional meaning of the intraepithelial compartment delimited by the M cells and its possible role is discussed.(ABSTRACT TRUNCATED AT 250 WORDS)

Arrangement of the small intestine lymphatic network in the Peyer's patches of the mouse. A light and transmission electron microscopic study.

The lymphatic network in Peyer's patches has been previously studied by scanning electron microscopy in rabbit and sheep. So far, data on the Peyer's patch lymphatic network obtained by light and transmission electron microscopy are still lacking. The present work was carried out on several series of consecutive thick and semithin sections of mouse Peyer's patches. Ultrastructural analyses were performed on ultrathin sections by traditional transmission electron microscopy. Lymph vessels were detected in the parafollicular and subfollicular areas of Peyer's patches. Two independent lymphatic plexuses, the muscularis mucosae lymphatic plexus and the subfollicular plexus, were identified respectively in the mucosal and submucosal layers. These lymphatic plexuses joined outside the patch, both draining into the submucosal lymphatic network of the small intestine. At the ultrastructural level, the muscularis mucosae lymphatic plexus, and the lymph vessels draining into it, showed a close association with bundles of smooth muscle cells. Numerous nerve fibres were detected in proximity to the lymphatic endothelium and, in some cases, synapse-like neuroendothelial associations were observed. We report here the lymph vessel organization observed in mouse Peyer's patches and discuss the meaning of the presence of subendothelial nerve terminals.

Uptake of a gram-positive bacterium (Streptococcus pneumoniae R36a) by the M cells of rabbit Peyer's patches.

The epithelium associated with the lymphoid follicles of Peyer's patches differs from the villi epithelium by the presence of M cells. The main function of these cells is to take up antigens (inert material, viruses and bacteria) from the intestinal lumen. The M cells are able to internalize various different gram-negative bacteria. In order to show the M cells ability to interact and take up a gram-positive bacterium, we exposed rabbit Peyer's patches to Streptococcus pneumoniae R36a. Using the isolated ileal loop technique, Peyer's patches were incubated with a bacterial suspension for varying periods (15, 30, 60, 100 minutes). The bacteria were found outside and inside the M cells. The internalized streptococci could be found in the M cell cytoplasm, in the cytoplasmic "pockets" and inside the intraepithelial lymphoid cells. The finding of internalized bacteria with their damaged walls suggests the possibility that M cells are able to modify internalized antigens in the same way as the antigen presenting cells.

Endocrine tissue associated with the pancreatic ductal system: a light and electron microscopic study of the adult rat pancreas with special reference to a new endocrine arrangement.

BACKGROUND: A substantial part of the endocrine pancreas has been previously described as being located either close to the excretory ducts as small clusters of endocrine cells and as Islets of Langerhans, or associated with the ducts as single endocrine cells scattered through the ductal epithelium. METHODS: Four Wistar white adult rats were sacrificed and perfused via the thoracic aorta with 2.5% glutaraldehyde. After the usual treatment for the transmission electron microscopy, pieces of pancreas were sectioned consecutively for light microscopy. Consecutive ultrathin sections were performed in the most interesting cases. RESULTS: The observations previously reported were confirmed. In addition, a new endocrine arrangement was detected and described as buds of endocrine cells (mainly B-cells) protruding from the ductal epithelium into the surrounding tissue. CONCLUSIONS: The authors propose to explain the endocrine buds as components of the gastro-entero-pancreatic system or as a stage of an endocrine pancreatic "neo-histogenesis" occurring in the adult rat pancreas.

A morphological study of the lymphocyte traffic in Peyer's patches after an in vivo antigenic stimulation.

BACKGROUND: Lymphoid cells have often been observed in the intestinal lumen and it has been hypothesized that M cells could represent one of the most important migration routes for the immunocompetent cells from the lymphoid follicle to the lumen. However, a direct evidence of the passage was lacking. In this study we describe a morphological analysis of the lymphocyte traffic in rabbit Peyer's patches after an in vivo stimulation with an antigen normally not present in the intestine. METHODS: The antigenic stimulation of a large number of Peyer's patches was carried out using the isolated ileal loop technique and then the samples from stimulated and control Peyer's patches were analysed by light and transmission electron microscopy. RESULTS: We have been able to describe details of lymphocyte migration through M cells, from the follicle to the intestinal lumen, and a marked increase of intraluminal lymphocytes by counting the immunocompetent cells after periods of antigenic stimulation of varying lengths. CONCLUSIONS: Our finding is that the passage of lymphocytes to the lumen is an antigen-dependent event and we also provide direct evidence that M cells are one of the migration routes. Our observations also indicate that lymphoid cells in the intestinal lumen may play an immunologic role in mucosal immunity.

A morphological study of the primary cilia in the rat pancreatic ductal system: ultrastructural features and variability.

Primary cilia in the pancreas of the rat were studied by transmission electron microscopy. Their presence is very common, and each ductal cell seems to be provided with a single cilium. The basal body showed anchoring apparatus such as transitional fibers and basal feet. The shaft can show a number of different patterns according to the level of the sections. Proceeding towards the tip, the microtubules decrease in number, although not always in the same way. Near the tip, it is possible to detect patterns, with only 1 microtubule. Three kinds of tips are described. The function of the cilia is discussed.

Histotopographic and ultrastructural study on the lymphatic network of the pancreas in the guinea pig.

The localization of absorbing lymph vessels was studied in the normal guinea pig pancreas by light microscopy (serial semithin sections) and transmission electron microscopy (ultrathin sections). Absorbing lymph vessels were observed both in the interlobular and intralobular areas where they can be localized close to the adenomeres. Lymph vessels were also seen in the interlobular areas located next to the islets of Langerhans and to groups of endocrine cells (n = 8-10) not showing a vascular organization comparable with islets of Langerhans. All lymph vessels in the pancreas are absorbing lymph vessels, characterized by a very thin endothelial wall, anchoring filaments and the absence of a definitive basal membrane. Adjacent endothelial cells form end-to-end, overlapping and interdigitating intercellular junctions. Valves were present both in the interlobular and intralobular lymph vessels.