Connective tissue in gut development: a key player in motility and in intestinal desmosis.

INTRODUCTION: Efficient intestinal peristalsis is a function of intact enteric nervous system, muscle, and connective muscularis propria tissue. Malfunction of any component results in impaired peristalsis. Hirschsprung disease (HD) as prototypic enteric neural migration disorder is increasingly well characterized. More recently, intestinal myopathies and particularly defects of myenteric collagenization have entered the focus of attention. However, detailed development of muscularis propria connective tissue is not well known. The aim of this study was to morphologically characterize intestinal connective tissue in fetal and postnatal development and intestinal pseudo-obstruction. MATERIALS AND METHODS: In this study, 130 archival specimens of fetal autopsies, intestinal resections, and biopsies were analyzed. Patients' age was 10th gestational week (gw) to 70 years. Muscularis mucosae, muscle layers, collagen tissue, and enteric plexus were analyzed. Picrosirius red stains, enzyme histochemistry, and immunohistochemistry for collagens I, III, and IV were performed. RESULTS: Total 89 normal intestinal specimens were from fetal autopsies or intestinal resections; 41 patients showed a primary structural colon wall defect (HD, desmosis). Our results showed a constant increase in tunica muscularis propria thickness with age. Separation into circular and longitudinal muscle layer first occurred in the 11th gw. A tendinous collagen plexus layer first arose in the 10th gw and showed a steady caliber increase. Muscularis mucosae first appeared in the 10th gw and grew independent of any primary gastrointestinal disease. In the 11th gw, enteric ganglia were fully developed. In desmosis, a collagen plexus layer was absent. In contrast, in HD, muscularis mucosae showed hypertrophy, but the collagen plexus layer was intact in the aganglionic segment. In intestinal neuronal dysplasia and hypoganglionosis, nerve cell development was disturbed; connective tissue and muscle layers were well developed. CONCLUSION: Our comprehensive study of intestinal connective tissue development in comparison to neural intestinal wall components in normal and pathological conditions showed that tendinous tissue develops parallel to muscularis propria and arises early in embryogenesis. In enteric nervous system disorders, ganglionic lesions develop independently of impaired collagen network, whereas mucosal biopsies serve for diagnosis of HD, seromuscular biopsies are required to prove desmosis in gastrointestinal dysmotility disorders.

The London Classification of gastrointestinal neuromuscular pathology: report on behalf of the Gastro 2009 International Working Group.

OBJECTIVE: Guidelines on histopathological techniques and reporting for adult and paediatric gastrointestinal neuromuscular pathology have been produced recently by an international working group (IWG). These addressed the important but relatively neglected areas of histopathological practice of the general pathologist, including suction rectal biopsy and full-thickness intestinal tissue. Recommendations were presented for the indications, safe acquisition of tissue, histological techniques, reporting and referral of such histological material. DESIGN: Consensual processes undertaken by the IWG and following established guideline decision group methodologies. RESULTS AND CONCLUSION: This report presents a contemporary and structured classification of gastrointestinal neuromuscular pathology based on defined histopathological criteria derived from the existing guidelines. In recognition of its origins and first presentation in London at the World Congress of Gastroenterology 2009, this has been named 'The London Classification'. The implementation of this classification should allow some diagnostic standardisation, but should necessarily be viewed as a starting point for future modification as new data become available.

The histopathology of gastrointestinal motility disorders in children.

Gastrointestinal motility disorders and chronic constipation are common pediatric problems. Symptoms of abdominal discomfort are frequently encountered in the daily practice of pediatricians and pediatric surgeons. Normal peristalsis depends on the interaction between muscles, nerve cells, and tendinous connective tissue of muscularis propria. Malfunction of any of these components results in a motility disorder. Aganglionosis, typically of the left distal colon, is the cause of Hirschsprung disease. Hypoganglionosis constitutes another gastrointestinal motility disorder. In hypoplastic hypoganglionosis, the number of nerve cells and the size of ganglia of the enteric nervous system are reduced, resulting in symptoms similar to aganglionosis. In intestinal neuronal dysplasia type B, submucous plexus development is disturbed. Immaturity of the enteric nervous system, but also ganglioneuromatosis, can be the underlying cause of chronic constipation. Chronic constipation may be caused by a myopathy. Aplasia or atrophy of the tendinous connective tissue of muscularis propria may cause desmosis, which may result in an aperistaltic syndrome. In severe chronic constipation, a histopathological diagnosis of the underlying cause is useful. In the diagnostic approach for most of these causes of chronic constipation, enzyme histochemistry is an efficient tool to complement conventional immunohistochemical and selected molecular technologies. An interdisciplinary approach of a gastrointestinal working group is beneficial in the management of these difficult patients.

Gastrointestinal neuromuscular pathology: guidelines for histological techniques and reporting on behalf of the Gastro 2009 International Working Group.

The term gastrointestinal neuromuscular disease describes a clinically heterogeneous group of disorders of children and adults in which symptoms are presumed or proven to arise as a result of neuromuscular, including interstitial cell of Cajal, dysfunction. Such disorders commonly have impaired motor activity, i.e. slowed or obstructed transit with radiological evidence of transient or persistent visceral dilatation. Whilst sensorimotor abnormalities have been demonstrated by a variety of methods in these conditions, standards for histopathological reporting remain relatively neglected. Significant differences in methodologies and expertise continue to confound the reliable delineation of normality and specificity of particular pathological changes for disease. Such issues require urgent clarification to standardize acquisition and handling of tissue specimens, interpretation of findings and make informed decisions on risk-benefit of full-thickness tissue biopsy of bowel or other diagnostic procedures. Such information will also allow increased certainty of diagnosis, facilitating factual discussion between patients and caregivers, as well as giving prognostic and therapeutic information. The following report, produced by an international working group, using established consensus methodology, presents proposed guidelines on histological techniques and reporting for adult and paediatric gastrointestinal neuromuscular pathology. The report addresses the main areas of histopathological practice as confronted by the pathologist, including suction rectal biopsy and full-thickness tissue obtained with diagnostic or therapeutic intent. For each, indications, safe acquisition of tissue, histological techniques, reporting and referral recommendations are presented.

Current concepts of enzyme histochemistry in modern pathology.

Enzyme histochemistry serves as a link between biochemistry and morphology. It is based on metabolization of a substrate provided to a tissue enzyme in its orthotopic localization. Visualization is accomplished with an insoluble dye product. It is a sensitive dynamic technique that mirrors even early metabolic imbalance of a pathological tissue lesion, combined with the advantage of histotopographic enzyme localization. With the advent of immunohistochemistry and DNA-oriented molecular pathology techniques, the potential of enzyme histochemistry currently tends to be underrecognized. This review aims to draw attention to the broad range of applications of this simple, rapid and inexpensive method. Alkaline phosphatase represents tissue barrier functions in brain capillaries, duodenal enterocyte and proximal kidney tubule brush borders. Decrease in enzyme histochemical alkaline phosphatase activity indicates serious functional impairment. Enzyme histochemical increase in lysosomal acid phosphatase activity is an early marker of ischemic tissue lesions. Over the last four decades, acetylcholinesterase enzyme histochemistry has proven to be the gold standard for the diagnosis of Hirschsprung disease and is one of the most commonly applied enzyme histochemical methods today. Chloroacetate esterase and tartrate-resistant phosphatase are both resistant to formalin fixation, EDTA decalcification and paraffin embedding. Early enzyme histochemical insight into development of a pathologic tissue lesion and evaluation of function and vitality of tissue enhance our understanding of the pathophysiology of diseases. In this process, enzyme histochemistry constitutes a valuable complement to conventional histology, immunohistochemistry and molecular pathology for both diagnostic and experimental pathology.

Diagnosis of megacystis-microcolon intestinal hypoperistalsis syndrome with aplastic desmosis in adulthood: a case report.

Megacystis-microcolon intestinal hypoperistalsis syndrome (MMHIS or Berdon syndrome) is an autosomal-recessive disorder characterized by chronic intestinal obstruction. Although the disease is often diagnosed in female infants we describe a man with late diagnosis in adulthood. Our patient presented soon after birth with intestinal obstruction and developed short bowel syndrome after multiple intestinal resections. Of note, the connective tissue net within the muscle layers of the intestinal wall was absent ('aplastic desmosis'). This case illustrates the variable clinical features of MMHIS and aplastic desmosis, which might delay the correct diagnosis of a severe disorder.

Intestinal neuronal dysplasia type B: one giant ganglion is not good enough.

In this "Current Practice in Pediatric Pathology" article, 2 experts in the field and an associate editor of Pediatric and Developmental Pathology discuss the definition, diagnosis, clinical significance, and management of intestinal neuronal dysplasia type B. Intestinal neuronal dysplasia type B has constituted a diagnostic challenge ever since its first description more than 30 years ago. Intestinal neuronal dysplasia type B is regarded by many as a subtle malformation of the enteric nervous system that is limited to the submucosal plexus of the colon. The precise etiology remains unknown, and, to date, no specific diagnostic test exists other than morphology. Over time, with increasing experience, obligate pathological features have been adapted and refined, leading to contemporary diagnostic criteria that are enunciated in this review and placed into context with prior published data. Rigorous application of these criteria, under standardized laboratory conditions, is crucial for accurate diagnosis and future advances in this field.

The pathogenesis of idiopathic megacolon.

BACKGROUND: Even today, the pathogenesis of idiopathic megacolon is still a subject of controversy. Anomalies of the gastrointestinal autonomous nervous system or of the smooth muscle of the muscularis propria are being considered. METHODS: Sixty-three idiopathic megacolon resections between 1997 and June 2004 were investigated. The native specimens were coiled caudo-cranially and cryostat-cut. Connective tissue was stained with picric acid/Sirius red after Delauney fixation. Immunohistochemistry was performed for collagen types I, II, III and IV, as well as smooth muscle actin, vimentin, desmin fibronectin and CD117 for interstitial cells of Cajal. The enteric nervous system was examined by enzyme histochemistry for acetylcholine-esterase, lactate dehydrogenase, succinic dehydrogenase and nitroxide synthase. RESULTS: Histologically, idiopathic megacolon was characterized by a total atrophy of the collagenous tendinous connective tissue membrane of the myenteric plexus and the tendinous collagen fibre net of the muscularis propria. Immunohistochemically, mainly collagen type III was missing in the muscularis propria. Interestingly, the incidence of idiopathic megacolon in those of the female sex was seven times more frequent than in the male sex. The myenteric plexus was normal in the majority of patients. Interstitial cells of Cajal, collagen II and IV, as well as smooth muscle actin, desmin and fibronectin showed no consistent alteration. CONCLUSION: A normally structured tendinous fibre net of muscularis propria is an essential prerequisite for effective gut peristalsis. Atrophy of the tendinous fibre net abolishes peristalsis and allows for unlimited distension of the colon. A diagnosis of idiopathic megacolon can reliably be made on a collagen stain. The normal findings of myenteric plexus support the hypothesis that a primary metabolic defect of muscularis propria may be the underlying cause of idiopathic megacolon.

Controversies concerning diagnostic guidelines for anomalies of the enteric nervous system: a report from the fourth International Symposium on Hirschsprung's disease and related neurocristopathies.

Intestinal Dysganglionoses (IDs) represent a heterogeneous group of Enteric Nervous System anomalies including Hirschsprung's disease (HD), Intestinal Neuronal Dysplasia (IND), Internal Anal Sphincter Neurogenic Achalasia (IASNA) and Hypoganglionosis. At present HD is the only recognised clinico-pathological entity, whereas the others are not yet worldwide accepted and diagnosed. This report describes the areas of agreement and disagreement regarding definition, diagnosis, and management of IDs as discussed at the workshop of the fourth International Meeting on "Hirschsprung's disease and related neurochristopathies." The gold standards in the preoperative diagnosis of IDs are described, enlighting the importance of rectal suction biopsy in the diagnostic workup. The most important diagnostic features of HD are the combination of hypertrophic nerve trunks and aganglionosis in adequate specimens. Acetylcholinesterase staining is the best diagnostic technique to demonstrate hypertrophic nerve trunks in lamina propia mucosae, but many pathologist from different centers still use H&E staining effectively. Moreover, the importance of an adequate intraoperative pathological evaluation of the extent of IDs to avoid postoperative complications is stressed. Although it is not clear whether IND is a separate entity or some sort of secondary acquired condition, it is concluded that both IND and IASNA do exist. Other interesting conclusions are provided as well as detailed results of the discussion. Further investigation is needed to resolve the many controversies concerning IDs. The fourth International Conference in Sestri Levante stimulated discussion regarding these entities and led to the International guidelines to serve the best interest of our patients.

Pathology of chronic constipation in pediatric and adult coloproctology.

In colonic motility disorders, a pathohistological diagnosis based solely on formalin-fixed gut is often inconclusive. Classical histological techniques or immunohistochemistry represent a static staining. In contrast, native tissue submitted to enzyme histochemistry provides functional information about the effectiveness of the cellular performance. Routinely, a complementary set of reactions is performed and includes acetylcholinesterase (AChE), lactic and succinic dehydrogenase, as well as nitroxide synthase reactions. In this monograph, the whole spectrum of different anomalies of the colonic wall is illustrated in a systematic fashion: Hirschsprung's disease is characterized by an increase in AChE activity of parasympathetic nerve fibers of the rectosigmoid. In ultrashort Hirschsprung's disease, only enzyme histochemistry renders a reliable diagnosis possible in biopsies of the anal ring. Aganglionosis of the musculus corrugator cutis ani shows a localized increase of AChE activity in nerve fibers, similar to Hirschsprung's disease, not detectable in conventional histology. Immaturity, hypoganglionosis and neuronal dysganglionosis can be clearly recognized in dehydrogenase reactions. Enzyme histochemical reactions are complemented by picrosirius red staining for assessment of the collagen texture of the muscularis propria. Absence or intertenial interruption of the continuous connective tissue layer between circular and longitudinal muscle of the muscularis propria has been termed aplastic or atrophic desmosis, respectively. Many of the entities described are also observed in adults. Atrophic hypoganglionosis or atrophic desmosis with loss of the myenteric plexus connective tissue fascia is implied as a frequent cause of chronic constipation in adults. The essential contribution of a functional histopathological technique towards a reliable diagnosis of gut dysfunction in native tissue is extensively demonstrated in great detail in more than two hundred figures.

Role of mitochondrial deterioration in physiological and pathological brain aging.

BACKGROUND: Mitochondria are widely reported to occupy a unique role in modulating cell viability, senescence and death. This is consistently supported by the multiple functions of these organelles. In addition to providing the energy for the myriad of cellular performances, mitochondria are involved in regulating thermogenesis, calcium buffering, integration of pro- and anti-apoptotic signals. OBJECTIVE: To stress the significant importance of subtle, continuous and permanent mitochondrial alterations as key events in physiological aging and as unfavourable determinants of age-related neurodegenerative diseases. RESULTS: Any dysfunction of these organelles may constitute a serious threat for cellular health status and survival, particularly of post-mitotic nerve and muscle cells. Mitochondrial deterioration may affect discrete features of the organelles (such as their structural dynamics, genetics and physiology) and lead to a progressive functional impairment. CONCLUSIONS: A variety of mitochondrial tasks, while hampering the possibility to recover the organelles' dysfunctions, offer different and reliable opportunities for therapeutic interventions.

Neuronal death versus synaptic pathology in Alzheimer's disease.

Neuron and synapse numeric densities as well as the average size and surface density of the synaptic junctional areas were measured in the hippocampus and cerebellum of adult, old, and demented (Alzheimer's disease) patients. Our findings support the notion that synaptic loss represents per se a prominent and early damage affecting zones of the central nervous system reported to show a different vulnerability to age- and pathology-related changes.

Morphometric quantification of normal submucous plexus in the distal rectum of adult healthy volunteers.

OBJECTIVE: Inadequate morphometric characterization of the normal adult submucous plexus has precluded the diagnosis of colonic dysganglionoses associated with constipation, such as intestinal neuronal dysplasia type B (IND B). The internal submucous plexus (Meissner plexus) was morphometrically quantified in adult healthy volunteers. DESIGN: Open, prospective morphometric study in balanced groups of female and male volunteers. PARTICIPANTS: Thirty-seven adult healthy male and female volunteers with normal bowel function and no history of gastrointestinal disease. METHODS: Four jumbo rectal biopsies (3-5 mm3) were taken 5 and 10 cm above the pectinate line. Two expert gastrointestinal pathologists assessed biopsy sections after specific nerve cell staining for lactic dehydrogenase, nitric oxide synthase and acetylcholinesterase, mainly for characteristics of ganglia and nerve cells in the submucous plexus. RESULTS: No healthy individual demonstrated over 20% of submucosal ganglia as giant ganglia or more than four giant ganglia per 30 sections (the morphometric criteria for IND B). Single submucosal nerve cells and ganglion numbers halved between 10 and 5 cm above the pectinate line, but there were no age or gender differences. The biological variability of nerve cell and ganglion density in the submucous plexus was large. CONCLUSIONS: Healthy adults show less than 20% of submucosal ganglia as giant ganglia and no more than four giant ganglia per 30 rectal biopsy sections. There is therefore no overlap with the histomorphological criteria of IND B. These data therefore support the specificity of the previously defined criteria for IND B in adults.