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F Merigo

Publications and source records attributed to F Merigo.

16 recordsLinked to original sources
PubMed2004

Neurochemistry of the gustatory subgemmal plexus.

Nerve fibers present in the basal plexus of the vallate papilla of the rat tongue were analyzed using cytochemical, immunocytochemical and ultrastructural methods to investigate whether the subgemmal plexus is subdivided into neurochemical compartments and to provide a clear definition of the reciprocal spatial relationships between nitrergic, peptidergic and acetylesterase positive structures. Several neuronal fibers were detected under the chemoreceptorial epithelium. Some of these fibers were in contact with the taste buds and in some cases neuronal projections were also present between the buds or inside them; some others fibers were present below this layer but in a more peripheral area. Antibodies against CGRP, SP and CCK stained fibers just below the chemoreceptorial epithelium, whereas fibers more distally located were immunolabeled by anti VIP, NOS-1 and NF-200 antibodies. Some double staining experiments were conducted using confocal microscopy. Other sections were processed cytochemically for AChE and subsequently for NADPH-d in colocalization experiments. All the data obtained using these techniques confirmed the results obtained with single immunostaining, as did the ultrastructural results. In conclusion, the present work demonstrates that the subgemmal plexus is a bilayered structure, suggesting that the complex relationship between the two layers plays a pivotal role in taste and in the control of processes ancillary to taste, such as control of vascular or secretory mechanisms.

Acetylcholine↗
PubMed2001

A brief survey of the modifications in sensory-secretory organs of the neonatal rat tongue.

Recent data obtained on rats suggest that in the days immediately following birth several events take place in the circumvallate papillae of the oral cavity. A phylogenetically primitive system of solitary chemosensory cells develops and is rapidly replaced by taste buds. The lipase-secreting von Ebner gland, which is associated with taste organs, begins to develop by forming short tubules. The intrinsic nervous system of the gustatory organs rapidly completes its maturation showing fast proliferation of fibers and immunocytochemical maturation. Intraepithelial lipid accumulation is visible in the non-receptorial mucosa of the tongue, showing aspects which suggest an active lipid secretion. These data demonstrate that in the rat the structure of the sensory-secretory organs of the newborn's tongue shows a typical conformation with respect to the adult and rapidly changes its organization in the first week after the birth. At the present level of knowledge, it is difficult to link the anatomical structures to peculiar functional roles but the rather simple organization of the neonatal gustatory epithelium could be in relation to the dietary regimen. The data obtained in laboratory animals underline the necessity of studies on human newborns to update the anatomical knowledge of the oral chemoceptive system.

Animals↗
PubMed2000

Postnatal development of the intrinsic nervous system in the circumvallate papilla-vonEbner gland complex.

We have studied the postnatal development of the intrinsic nervous system in the circumvallate papilla-vonEbner gland complex using NADPH-diaphorase cytochemistry, immunocytochemistry (for nitric oxide synthase-1 and alpha-internexin) and electron microscopy. In rats sacrificed in their first day post partum (1 p.p.), only isolated NADPH-diaphorase positive neurons were visible in the organ. At 2 p.p., a small group of neurons was visible at the base of the papillae and positive neurons formed short chains close to the developing glandular tubules. In the following days, the NADPH-diapharase positive cells increased in number and nerve fibres were associated to small ganglia located at the base of the papilla or in the gland. After the first week of extrauterine life, the intrinsic nervous system was similar to the intrinsic system of adult animals. An immunocytochemical positivity for nitric oxide synthase-1 appeared at 4 p.p. in neurons located in the gland and at 7 p.p. in cells located at the base of the papilla. Immunocytochemical staining for alpha-internexin showed that at 1 p.p. developing nerve fibres were present in the connective tissue of the tongue's muscle layer. At 2-3 p.p., developing nerve fibres were also present at the bases and in the core of the papilla. In the following days, the positivity for alpha-internexin was reduced and one week after birth was virtually absent. Ultrastructural examination revealed that since 1 p.p. isolated neurons can be found at the base of the papilla. In conclusion, the intrinsic nervous system originates from neurons present in the organ at the birth which, in the first days, undergo a biochemical and morphological maturation while the nerve fibres rapidly grow. These findings support the hypothesis that the intrinsic nervous system of the circumvallate papilla has a role in the maturation of the vonEbner gland.

Animals↗
PubMed1999

Neuropeptide expression in the mouse vomeronasal organ during postnatal development.

The expression of selected regulatory neuropeptides was investigated by immunohistochemistry in nerves supplying the vomeronasal organ (VNO) of mice during postnatal development. Results show that neurons in the VNO are devoid of immunolabeling with any of the antibody used from 1 day to 2 months of age. In the non-receptor epithelium (NRE) and the vomeronasal vascular pump (VP) the timing of expression of regulatory neuropeptides differed among neuropeptides and the different VNO structures. Regulatory neuropeptides usually found in sensory nerves (substance P, calcitonin gene-related peptide) and efferent nerves (neuropeptide Y, atrial natriuretic peptide) are expressed in the NRE and the VP, respectively. These results support the view that the VNO is to some extent functional during postnatal development.

Animals↗
PubMed1999

Immunohistochemical investigation of the vomeronasal organ. Nitric oxide synthase expression in the mouse during postnatal development.

The expression of nitric oxide synthase type I (NOS-I), the key enzyme for the synthesis of the gaseous neurotransmitter nitric oxide, was investigated by means of immunohistochemistry in the vomeronasal organ (VNO) of mice from postnatal day 1 for 2 months. The results show that NOS is expressed in extrinsic nerve supplying the developing erectile tissue of VNO (the so-called VNO pump) as well as blood vessels in the connective tissue laying under the receptor epithelium at postnatal day 1. At 8, 15 and 21 postnatal days, and at 2 months the density of NOS-1-immunoreactive nerves goes along with the development of the erectile tissue. From postnatal day 8 onwards, NOS-1-immunoreactive fibers are found also in the vicinity of the VNO glands. These data suggest that nitric oxide (NO) modulates VNO activity early after birth in the mouse.

Age Factors↗
PubMed1999

alpha-Gustducin expression in the vomeronasal organ of the mouse.

The expression of alpha-gustducin, a G protein alpha subunit involved in bitter and sweet taste transduction, was investigated in chemosensory tissues of adult mice. By immunohistochemistry, alpha gustducin was absent in the olfactory neuroepithelium. Instead, alpha gustducin was expressed in a subset of bipolar cells in the proliferative zone of the vomeronasal neuroepithelium as well as in taste buds. Northern blot analysis confirmed the presence of alpha gustducin in isolated vomeronasal organs. Moreover, immunohisto- chemistry revealed the expression of alpha gustducin in scattered cells of the nasal respiratory epithelium. These results show for the first time that alpha gustducin is expressed in chemosensory tissue outside the alimentary tract, suggesting that common transduction mechanisms could be shared by apparently unrelated chemosensory tissues.

Animals↗
PubMed1999

Immunohistochemical evidence suggests intrinsic regulatory activity of human eccrine sweat glands.

Immunohistochemistry of normal eccrine sweat glands was performed on paraffin sections of human skin. Immunoreactivity (ir) for neuron specific enolase, S100 protein (S100), regulatory peptides, nitric oxide synthase type I (NOS-I) and choline-acetyltransferase (ChAT) was found in small nerve bundles close to sweat glands. In the glands, secretory cells were labelled with anticytokeratin antibody. Using antibodies to S100, calcitonin gene-related peptide (CGRP) and substance P (SP) a specific distribution pattern was found in secretory cells. Granulated (dark) and parietal (clear) cells were immunopositive for CGRP, and S100 and SP, respectively. Immunoreactivity was diffuse in the cytoplasm for CGRP and S100, and peripheral for SP. Myoepithelial cells were not labelled. Electron microscopy revealed electron dense granules, probably containing peptide, in granulated cells. Using antibodies to NOS-I and ChAT, ir was exclusively found in myoepithelial cells. Immunoreactivity for the atrial natriuretic peptide was absent in sweat glands. These results provide evidence for the presence of both regulatory peptides involved in vasodilation and key enzymes for the synthesis of nitric oxide and acetylcholine in the secretory coil of human sweat glands. It is suggested that human sweat glands are capable of some intrinsic regulation in addition to that carried out by their nerve supply.

Adult↗
PubMed1996

Fat body of the frog Rana esculenta: an ultrastructural study.

In the frog, the fat body is the largest body lipid deposit and is associated with the gonad. The aim of the present work was to investigate the fine structure of the fat body at different periods of the annual cycle and during prolonged starvation. Results indicate that fat body cells of Rana esculenta caught in autumn and after winter hibernation resemble mammalian adipocytes of white adipose tissue and contain markers of adipose tissue, such as S-100 protein and lipoproteinlipase. However, unlike mammalian adipocytes, fat body adipocytes consistently show small lipid droplets associated with their single, large lipid deposits, a lack of a definite external lamina, and the presence of cellular prolongations and spicula at their surfaces. Transmission and scanning electron microscopy in association with lanthanum tracer experiments suggest that in fat body adipocytes a vesicular-tubular system connects the cytoplasm and the interstitial space. In June (i.e., during the reproductive period), fat body adipocytes appear to have lost much of their lipid deposit and adjacent adipocytes show interdigitation of their plasma membranes and prominent Golgi complexes. In starved frogs, fat body cells can be almost devoid of lipid and in regression to a near-mesenchymal state. Nevertheless, these fat bodies still contain lipoproteinlipase activity (approximately 45% of that found in lipid-filled ones), indicating persistent adipose differentiation of the cells therein. Results presented here show that the R. esculenta fat body is an adipose organ undergoing reversible extreme changes in adipocyte fat content, which are associated with definite ultrastructural features. The fat body represents a suitable model for studying adipose tissue under different and extreme physiological conditions.

Adipocytes↗
PubMed1995

Adipocyte morphology during hormone-induced lipid deposition and mobilization. An ultrastructural investigation in the perfused cardiac fat.

The rat pericoronary adipose tissue was perfused in the presence of either the liposynthetic hormone insulin or the lipolytic hormone noradrenaline. Insulin perfusion associated with a) larger adipocyte mean sectional diameter in comparison with noradrenaline perfusion; b) glycogen deposition; c) appearance of small fat globules at discrete sites at the periphery of the main lipid drop. The two latter phenomena were apparently dose-dependent. Massive lipid deposition was induced by addition of triglycerides to the perfusion medium and this associated with appearance of prominent endoplasmic reticulum in the cytoplasm. In noradrenaline-perfused adipose tissue many small lipid droplets surrounded the central lipid deposit and the endoplasmic reticulum was in the form of both thin long, dashed cisternae sometime surrounding lipid droplets and grouped, anastomosing tubular cisternae. The present work shows that the perfused white adipose tissue of the heart is a suitable model to study, in situ, the morphological effects of hormones in adipocytes.

Adipocytes↗
PubMed1994

Magnetic resonance imaging of the submandibular-sublingual complex.

The submandibular-sublingual complex (SSC) was studied in vivo by magnetic resonance imaging (MRI) at 4.7 and 7.05 Tesla in rat and mouse. A correlation was found between histology and MRI signal. The mainly mucous sublingual gland emitted a more intense signal than the mainly serous submandibular gland. Ventral to the glands, cutis, subcutaneous adipose tissue and two planes of muscular tissue separated by connective laminae were visible in vivo. Autopsy and histology confirmed the in vivo description provided by MRI. The reactivity of the salivary system after pharmacological stimulation was studied in mice at 7.05 Tesla. Stimulation of salivary secretion by pilocarpine nitrate injected in the subcutaneous space ventrally to the SSC resulted in an augmentation of the salivary liquid visible in the oral cavity by MRI. The diffusion of pilocarpine nitrate in the connective tissue located ventrally the SSC and in the glandular parenchyma was also followed in vivo. These results show that MRI is a potentially useful tool for studying the salivary glands in vivo.

Animals↗
PubMed1988

Pancreatic function in chronic inflammatory bowel disease.

This study was prospectively carried out to evaluate the frequency and clinical significance of pancreatic impairment in the course of chronic inflammatory bowel disease (CIBD). Twenty-seven patients affected by ulcerative colitis or Crohn's disease were submitted to a secretin-cerulein test, oral glucose test (OGT) and to indirect immunofluorescence (IFL) for detection of autoantibodies against exocrine and endocrine tissue. A bicarbonate plus enzyme or only an enzyme insufficiency was found in 11/27 patients, whereas isolated lipase decrease was observed in 18 subjects. In the results of the OGT and the indirect IFL test there was no difference between patients and controls. These data demonstrate that pancreatic impairment is a far more frequent occurrence than generally recognized in clinical practice. The decrease of lipase secretion could worsen the consequences of malabsorption in Crohn's disease of the small intestine. Therefore we think that a pancreatic assessment is advisable, at least in Crohn's disease patients with steatorrhea.

Adult↗
PubMed1987

HLA molecule expression on chronic pancreatitis specimens: is there a role for autoimmunity? A preliminary study.

This study was prospectively carried out in order to clarify if an aberrant expression of HLA-DR molecules could take part in the pathogenesis of chronic pancreatitis. Pancreatic specimens from 12 chronic pancreatitis patients and nine controls were examined. Strong HLA-DR expression was observed in 6/12 chronic pancreatitis patients and in 1/9 controls. Moreover, lymphocytic foci with large numbers of activated cells were found only in chronic pancreatitis. The four HLA-DR - patients had a marked increase of fibrous tissue with small portions of acinar tissue, whereas the six patients with strong positivity had the greatest dilatation and hyperplasia of the ducts. These findings are similar to those observed in immune diseases, such as thyroiditis and primary biliary cirrhosis (PBC), and suggest that autoimmune phenomena are involved in chronic pancreatitis.

Adult↗
PubMed1985

Association of chronic alcoholic liver and pancreatic disease: a prospective study.

Seventy-two chronic alcoholics, 40 (all males) with chronic pancreatitis and 32 (23 males and nine females) with liver cirrhosis, were submitted to liver biopsy, endoscopic retrograde cholangiopancreatography and secretin-caerulein test in order to assess a possible liver involvement in chronic pancreatitis and viceversa, and to evaluate the existence of any relationship between the diseases of these two organs. Chronic pancreatitis patients were younger than cirrhotic patients and drank more than the cirrhotic females. Twenty-nine of the 40 patients had abnormal liver histology, five had micronodular cirrhosis and were older than the others. No relationship was found between the degree of pancreatic impairment and the type of liver injury. Five liver cirrhosis patients had an endoscopic retrograde cholangiopancreatography picture consistent with chronic pancreatitis; two were females with an alcohol intake lower than the one of the other females. In conclusion the association of chronic pancreatitis and liver cirrhosis was observed in a minority of cases, with the same percentage in the two groups, even if the cirrhotic subjects were older than the pancreatitics. Therefore we can postulate that different factors have roles in the pathogenesis of alcoholic cirrhosis and of chronic alcoholic pancreatitis. The association of the two diseases in two women with a relatively low alcohol intake supports this hypothesis.

Adult↗
PubMedDate not supplied

Ultrastructural phenotype of "intestinal-type" cells in columnar-lined esophagus.

An intestinal-type epithelium is often present at columnar-lined esophagus, gastroesophageal junction or within the so-called short segment Barrett's esophagus, but ultrastructural study failed to detect enterocytes in columnar-lined esophagus. The authors have analyzed the intestinal aspects present in areas of columnar-lined esophagus in a population of patients with reflux esophagitis to better understand the morphology and histogenesis of the proliferating elements. Columnar-lined mucosa was studied in 35 patients. Columnarsurface cells displayed a wide spectrum of ultrastructural features. Well-differentiated columnar secretory cells, secretory-absorptive cells, poorly differentiated columnar cells, atypical columnar cells, and goblet cells were detected. Well-differentiated absorptive cells were never found, These results demonstrate that the areas of intestinal metaplasia show a wide spectrum of ultrastructural phenotypes, ranging from poorly to well-differentiated cells. However, true enterocytes were not found and the most represented phenotype is that of secretory-absorptive cells, whose principal characteristic is the presence of secretory and absorptive aspects together. They can be described as secretory enterocytes or cells with double specialization. To the authors' knowledge, similar cells were not previously described in normal intestinal mucosa, and ultrastructural studies are consistent in describing a broad spectrum of ultrastructural features, suggesting that Barrett's specialized metaplasia is derived from cells with the capacity for a wide range of differentiation. Therefore, despite the wide use of term intestinal metaplasia in the medical literature, experimental data clearly failed to detect enterocytes in the columnar-lined esophagus, and ultrastructural data do not support the concept of intestinal metaplasia. The cellular heterogeneity seems to be the result of a "phenotypic shift" of undifferentiated elements, which show a different pattern of evolution. The result of this process is the formation of new cell types dissimilar from those normally present in esophageal, gastric, or duodenal mucosa.

Adolescent↗
PubMedDate not supplied

Neuronal intermediate filaments in the developing tongue of the frog Rana esculenta.

The expression of several neuronal intermediate filament (NIF) proteins was investigated in the tongue of metamorphosing tadpoles (stage 38-45 of Gosner) and in adult individuals of the frog, Rana esculenta by means of immunohistochemistry. Results showed that nerve fibres at early stages of tongue development expressed peripherin (a NIF protein usually found in differentiating neurones) as well as the light- and medium molecular weight NIF polypeptide subunits (NF-L and NF-M, respectively); in the adult frog, peripherin was still found in nerve fibres reaching the fungiform papilla together with NF-M, but NF-L immunoreactivity was absent therein. Clusters of epithelial cells expressing peripherin were found in the early developing tongue before differentiation of taste organs, and NF-L and NF-H immunoreactivities were present in basal (Merkel) cells of the adult frog taste disc. Results indicate that neurones innervating the adult frog's taste disc maintain a certain plasticity in their cytoskeleton and that neuronal-like cells are present in the undifferentiated and differentiated tongue epithelium possibly playing a role in the developing and mature taste organ.

Animals↗