Enteric nerves and interstitial cells of Cajal are altered in patients with slow-transit constipation and megacolon

BACKGROUND & AIMS: A variety of gastrointestinal motility disorders have been attributed to alterations of interstitial cells of Cajal and malformations of the enteric nervous system. This study evaluates both the distribution of interstitial cells of Cajal and the pathohistology of the enteric nervous system in 2 severe human colorectal motility disorders. METHODS: Colonic specimens obtained from patients with slow-transit constipation (n = 11), patients with megacolon (n = 6), and a control group (n = 13, nonobstructing neoplasia) were stained with antibodies against c-kit (marker for interstitial cells of Cajal) and protein gene product 9.5 (neuronal marker). The morphometric analysis of interstitial cells of Cajal included the separate registration of the number and process length within the different regions of the muscularis propria. The structural architecture of the enteric nervous system was assessed on microdissected whole-mount preparations. RESULTS: In patients with slow-transit constipation, the number of interstitial cells of Cajal was significantly decreased in all layers except the outer longitudinal muscle layer. The myenteric plexus showed a reduced ganglionic density and size (moderate hypoganglionosis) compared with the control group. Patients with megacolon were characterized by a substantial decrease in both the number and the process length of interstitial cells of Cajal. The myenteric plexus exhibited either complete aganglionosis or severe hypoganglionosis. CONCLUSIONS: The enteric nervous system and interstitial cells of Cajal are altered concomitantly in slow-transit constipation and megacolon and may play a crucial role in the pathophysiology of colorectal motility disorders.     

Deficiency of interstitial cells of Cajal in the small intestine of patients with Crohn''s disease

OBJECTIVE: Interstitial cells of Cajal are critical for the generation of electrical slow waves that regulate the phasic contractile activity of the tunica muscularis of the GI tract. Under certain pathophysiological conditions loss of interstitial cells of Cajal may play a role in the generation of certain motility disorders. The aim of the present study was to determine if there is an abnormality in the density or distribution of interstitial cells of Cajal from patients with Crohn's disease. METHODS: Small intestines from control subjects and patients with Crohn's disease were examined using immunohistochemistry and antibodies against the Kit receptor, which is expressed in interstitial cells of Cajal within the tunica muscularis of the GI tract. The density and distribution of interstitial cells of Cajal were assessed in the longitudinal and circular muscle layers and in the myenteric and deep muscular plexus regions of Crohn's and control tissues. RESULTS: Tissues from Crohn's disease patients showed an almost complete abolition of interstitial cells of Cajal within the longitudinal and circular muscle layers and a significant reduction in numbers at the level of the myenteric and deep muscular plexuses. CONCLUSIONS: In tissues from Crohn's disease patients, the density of interstitial cells of Cajal was reduced throughout the tunica muscularis in comparison to control small intestines. The disturbance of intestinal motility that occurs in patients with Crohn's disease may be a consequence of the loss of or defects in specific populations of interstitial cells of Cajal within the tunica muscularis.     

Spectrum of histopathologic findings in patients with achalasia reflects different etiologies

BACKGROUND: The etiology of achalasia is still unknown. The aim of the present study was to elucidate its underlying pathologies and their chronology by investigation of esophageal specimens in patients undergoing surgery (esophageal resection or myotomy) for achalasia. METHODS: In 17 patients with achalasia, histopathologic examinations of the esophageal wall focussing on the myenteric plexus were performed. Preoperative diagnosis was based on clinical evaluation, esophagogastroscopy, barium esophagogram in all, and esophageal manometry in eight patients. The median age at the time of surgery was 54 years (range: 14-78 years). In eight cases, the complete esophageal, body and in nine cases a smooth muscle biopsy including parts of the myenteric plexus from the distal part of the esophagus (high pressure zone) was available. The tissue specimens were fixed in formalin and embedded in paraffin. The staining procedures were hematoxylin and eosin (HE), Elastica van Gieson (EvG), and periodic acid-Schiff (PAS) reaction. Immunohistochemical examinations were performed with antibodies against B and T lymphocytes, neurofilament, protein gene-related product (PGP 9.5), S-100 protein, myosin, desmin, smooth muscle actin and substance P. RESULTS: In 13 of 17 patients, a significant reduction of the number of intramural ganglion cells was present. Common findings were a severe fibrosis of the smooth muscle layer (10/17) and obvious myopathic changes of the smooth muscle cells (5/17). Staining for B and T lymphocytes found signs of inflammation in mucosal and muscular areas. Three patients exhibited a marked invasion of eosinophilic granulocytes of the muscularis propria (eosinophilia). Esophageal carcinoma had developed in three patients (squamous cell carcinoma in two and carcinoma in situ in another patient with Barrett's esophagus and high-grade dysplasia). Severe inflammatory reactions (neural, eosinophilic and mucosal) dominated in patients with a longstanding history of achalasia (>10 years) as well as a marked endomysial fibrosis. CONCLUSIONS: The histopathological investigations of the esophageal wall in 17 patients undergoing esophageal resection or myotomy for achalasia suggest that the reduction of intramural ganglion cells might be a secondary change, probably due to inflammation triggered by autoimmune mechanisms or a chronic degenerative process of the central and/or peripheral part of the vagal nerve. The primary lesion could also be a severe myopathy of the smooth muscle cells.     

Matrix Composition in Opossum Esophagus

The esophagus of mammalian species is organized into mucosa, connective tissue, and muscle, but little is known about the matrix of these layers. We studied by immunohistochemistry the distribution of collagens, fibronectin, versican, and elastin in the smooth muscle segment of the American opossum. Cryosections were exposed to specific antibodies and fluorescent-stained using conjugates of rhodamine or isothiocyanate. Staining was scored by two observers. We found that collagen I was prominent in the submucosa and in the muscular septa; collagen III formed fibrillar meshes in the lamina propria and the submucosa but was virtually absent from the epithelial and muscular layers; collagen IV was restricted to the base of the epithelium; collagen V, in contrast to collagen III, was prominent in epithelium and muscularis mucosae and sparse in muscular septa and submucosa. Fibronectin distribution followed collagen III; it formed layers in lamina propria and submucosa and strands in muscle septa and between individual muscle cells. Versican distribution followed collagen V; it was prominent in large muscle septa and formed thick sheets at the boundaries of submucosa/circular muscle and of circular/longitudinal muscle. We also determined the tissue contents of protein, hexuronic acid, and fibronectin. The mucosal layers exceeded the muscular layers in their content of hexuronic acid and fibronectin but not protein. We conclude that individual layers of the smooth muscle esophagus each have their own characteristic matrix. Lamina propria and submucosa are similar with regard to fiber orientation but lamina propria contains relatively more collagen III (small fibril) and submucosa comparatively more collagen I (large fibril). Nonfibrillar collagen V and versican are particularly prominent specifically on the boundaries between contracting muscle tissue and connective tissue framework.     

Megacolon in myotonic dystrophy caused by a degenerative neuropathy of the myenteric plexus

A 32-yr-old man with myotonic dystrophy had a left hemicolectomy performed because of a megacolon. The colonic mucosa, smooth muscle, and connective tissue appeared normal by hematoxylin and eosin and trichrome stains and transmission electron microscopy. In contrast, the myenteric plexus had markedly fewer neurons than normal on the hematoxylin and eosin stains. Silver staining of the plexus revealed degeneration and decreased numbers of argyrophilic neurons, which were smaller and had fewer processes and a more uneven staining quality than controls. Many axons were fragmented, and increased numbers of glial cell nuclei were present in the plexus. Degenerative changes in the neurons were present in a patchy distribution on transmission electron microscopy. Immunohistochemistry revealed a decrease of the substance P- and enkephalin-immunoreactive fibers in the muscularis externa. This suggests that colonic motor dysfunction associated with myotonic dystrophy may be caused by a visceral neuropathy that involves the substance P- and enkephalin-immunoreactive fibers of the smooth muscle.     

Immunohistochemical study of the colonic muscle and innervation in idiopathic chronic constipation

PURPOSE: This study was designed to investigate neural and muscular features of the colonic wall in patients with severe idiopathic constipation. METHODS: By using quantitative immunohistochemistry, resected specimens from 14 patients with idiopathic chronic constipation and 17 nonobstructed cancer controls were studied. RESULTS: Routine histology revealed no significant histologic abnormality throughout the colon apart from four cases of melanosis coli. Ratio of the thickness of circular to longitudinal muscle was significantly lower in the left colon in constipated subjects. The myenteric plexus appeared morphologically normal in all subjects. S-100 protein, which stains neuronal supporting tissues, demonstrated an increase in the proportion of neural tissue in the myenteric plexus. There was an increased number of PGP-9.5 immunoreactive nerve fibers in the muscularis propria in constipated patients, and this was significantly higher in the ascending and descending colon. CONCLUSION: Intractably constipated patients have alterations in the neural composition of the colonic myenteric plexus and innervation of the circular muscle.Supported by a grant from Yonsei University Research Foundation, Seoul, Korea. Dr. Talbot is supported in part by the Imperial Cancer Research Fund.     

Pan-colonic decrease in interstitial cells of Cajal in patients with slow transit constipation

BACKGROUND: Interstitial cells of Cajal (ICC) are required for normal intestinal motility. ICC are found throughout the human colon and are decreased in the sigmoid colon of patients with slow transit constipation. AIMS: The aims of this study were to determine the normal distribution of ICC within the human colon and to determine if ICC are decreased throughout the colon in slow transit constipation. PATIENTS: The caecum, ascending, transverse, and sigmoid colons from six patients with slow transit constipation and colonic tissue from patients with resected colon cancer were used for this study. METHODS: ICC cells were identified with a polyclonal antibody to c-Kit, serial 0.5 microm sections were obtained by confocal microscopy, and three dimensional software was employed to reconstruct the entire thickness of the colonic muscularis propria and submucosa. RESULTS: ICC were located within both the longitudinal and circular muscle layers. Two networks of ICC were identified, one in the myenteric plexus region and another, less defined network, in the submucosal border. Caecum, ascending colon, transverse colon, and sigmoid colon displayed similar ICC volumes. ICC volume was significantly lower in the slow transit constipation patients across all colonic regions. CONCLUSIONS: The data suggest that ICC distribution is relatively uniform throughout the human colon and that decreased ICC volume is pan-colonic in idiopathic slow transit constipation.     

Enteric innervation in idiopathic megarectum and megacolon

We have studied the resection specimens from 5 patients with idiopathic megarectum and megacolon and 10 control subjects with non-obstructing colonic cancer. Histological staining with haematoxylin and eosin, and immunocytochemical staining for protein gene product 9.5 (PGP 9.5), S100 protein, vasoactive intestinal polypeptide (VIP) and calcitonin gene-related peptide (CGRP), and histochemical localization of NADPH diaphorase was performed. The amount of VIP and CGRP present in samples was measured using an enzyme-linked immunosorbent assay. Patients with idiopathic megarectum and megacolon showed hypertrophy of the muscularis mucosae and muscularis externa. The architecture of the innervation as assessed by immunoreactivity for PGP 9.5 and S100 protein appeared normal. There was a decrease in the density of innervation of the longitudinal muscle in rectal tissue from patients with idiopathic megarectum, with fewer VIP- and NADPH-diaphorase-containing nerves. In the muscularis mucosae and lamina propria of the rectal samples of patients with idiopathic megarectum, VIP immunoreactivity was higher and more NADPH-diaphorase-containing nerves were seen. CGRP-immunoreactive nerve fibres were only seen in the myenteric plexus. No CGRP-immunoreactive cell bodies were seen. In summary, there is an increase in VIP and nitric oxide containing fibres in the muscularis mucosae and lamina propria and a decrease in the longitudinal muscle in rectal tissue of patients with idiopathic megarectum. Both are NANC (nonadrenergic noncholinergic) inhibitory transmitters in the gut and the possible relationship of the changes in their density with gut function is discussed.

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Résumé. Nous avons étudié les pièces opératoires de cinq patients traités pour un mégarectum idiopathique et un mégac?lon et celles de dix sujets témoins traités pour un cancer colique non obstructif. Les coupes histologiques ont été colorées à l'hématoxine-éosine et avec des colorants immuno-histo-chimiques pour la protéine génique 9.5 (PGP 9.5), la protéine S100, les polypeptides intestinaux vaso-actifs (VIP) et le peptide de la calcitonine (CGRP) ainsi que pour la localisation histo-chimique de la diaphorase NADPH. Les concentrations de VIP et de CGRP présents dans les échantillons ont été mesurées au moyen d'un essai immuno-absorbant enzymatiquement lié. Les patients avec un mégarectum idiopathique et un mégac?lon présentaient une hypertrophie de la muscularis mucosae et de la musculature externe. L'architecture de l'innervation déterminée par l'immuno-réactivité pour le PGP 9.5 et la protéine S100 appara?t comme normale. Il y a une diminution de la densité de l'innervation de la musculature longitudinale du rectum chez les patients avec un mégarectum idiopathique, ainsi qu'une diminution des nerfs contenant de la VIP et de la diaphorase-NADH. Dans la muscularis mucosae et dans la lamina propria, des échantillons de rectum des patients avec un mégarectum idiopathique, l'immuno-réactivité pour la VIP était plus haute et les nerfs contiennent davantage de diaphorase NADPH. L'immuno-réactivité pour le CGRP et fibres nerveuses n'a été retrouvée que dans le plexus myentérique. Aucune inclusion celulaire immuno-réactive pour CGRP n'a été observée. En résumé, il y a une augmentation des fibres contenant VIP et des oxydes nitriques. Dans la muscularis mucosae et la lamina propria et une diminution pour ces substances dans la musculature longitudinale des patients avec un mégarectum idiopathique. Tous deux sont des transmetteurs inhibiteurs NANC de l'intestin (non adrénergiques et non cholénergiques) et une relation possible dans les changements de leur densité avec la fonction intestinale est discutée.

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Accepted: 18 August 1996     

Altered colonic transit in TNBS-induced experimental colitis in guinea pig and distribution of nitric oxide synthase in the colonic wall]

BACKGROUND/AIMS: Inflammation-induced alterations in smooth muscle contractility may be due to the effects on smooth muscle itself, neurotransmitters or enteric nerves. In dextran sulfate sodium-induced colitic rat, the delay in colonic transit was caused by decreased activity and production of neuronal nitric oxide synthase (nNOS) in the myenteric plexus of the distal colon. The aim of this study was to investigate the relationship between the delay in colonic transit and the distribution of inducible NOS (iNOS) and nNOS immunoreactive cells in the myenteric plexus of trinitrobenzene sulfonic acid (TNBS)-induced colitic guinea pig. METHODS: Sacrificed and their colonic tissues of forty-five TNBS-induced colitic guinea pigs were used to measure the colonic transit, and analyzed by immunohistochemistry. RESULTS: Colonic transit was delayed significantly at 3, 7 and 14 days after administration of TNBS. In control, nNOS immunoreactivity was present in the mucosa, submucosa, lamina propria, and ganglion cells of the myenteric plexus, while after TNBS treatment, reduced nNOS cells were found. However, the number of nNOS ganglion cells in the myenteric plexus was similar to those seen in controls. After administration of TNBS, iNOS immunoreactivity was increased in the mucosa and submucosa, but the number of iNOS positive ganglion cells in the myenteric plexus was not changed compared to control. CONCLUSIONS: It is suggested that in TNBS-induced guinea pig colitis, delayed colonic transit is not associated with the expression of nNOS nor iNOS in the myenteric plexus.     

Intestinal pseudoobstruction caused by diffuse lymphoid infiltration of the small intestine

Four young women presented with diarrhea, malabsorption, and intestinal pseudoobstruction. Intestinal biopsy specimens (both peroral and full-thickness) showed flat small intestinal mucosa, sparsity of crypts, and a widespread lymphoid infiltrate in the lamina propria, muscularis propria, and myenteric plexus. There was no neuron or nerve fiber loss or damage in the plexus; muscle cell absence in the vicinity of lymphoid cell infiltration in the muscularis propria probably accounted for the pathogenesis of pseudoobstruction. Immunochemical stains showed that the infiltrate was polyclonal, and none of the patients has developed lymphoma on clinical follow-up of 4-16 yr. Transient improvement in symptoms occurred after antibiotic therapy in 3 patients, and 1 patient had improvement after treatment with cyclophosphamide and prednisone; however, symptoms of pseudoobstruction persist in all. These cases illustrate yet another cause of intestinal pseudoobstruction which is histologically distinct from visceral myopathies and neuropathies. The pathogenesis of this illness may be related to that of diffuse immunoproliferative diseases seen in Third World countries.     

Major histocompatibility class II expression on the small intestinal nervous system in Crohn's disease.

Widespread alterations of the gut autonomic nervous system have been described in Crohn's disease. Immunohistochemistry shows that these alterations are associated with the expression of major histocompatibility (MHC) class II antigens (HLA-DR) on enteroglial cells in the ganglia of the submucous and myenteric plexuses and on the enteroglial sheaths of the nerve extensions. Neuronal cell bodies and extensions do not express MHC class II antigens. The class II expression is associated with the presence of UCHL1-positive T lymphocytes. MHC class II expression can also be found on endothelial cells and vascular smooth muscle cells but not on smooth muscle cells of the muscularis mucosae or propria. The intensity of MHC class II expression on the glial cells of the enteric nervous plexus and on endothelial cells correlates well with the intensity of class II expression on epithelial cells.     

Chronic idiopathic intestinal pseudo-obstruction caused by a degenerative disorder of the myenteric plexus: the use of Smith's method to define the neuropathology

In this paper we report the pathologic basis of chronic idiopathic intestinal pseudo-obstruction in a patient who had a subtotal colectomy and ileorectal anastomosis for severe obstipation. Conventional light microscopy of the resected intestine showed an increased thickness of the longitudinal muscle, minimal amounts of smooth muscle fibrosis, and normal smooth muscle cells. The morphology of the myenteric plexus was difficult to interpret with this technique, but quantification of colonic neurons revealed a significantly decreased number compared with controls. Silver stains of the myenteric plexus by Smith's method showed: (a) patchy loss of nerve tracts with replacement by Schwann cells, (b) degeneration and decreased numbers of both argryophilic and argyrophobic neurons, (c) fragmentation and dropout of many axons, and (d) increased thickness and disorganized spatial arrangement of other axons. The pathology of this intestinal neuropathy could be missed by conventional light microscopy and may be apparent only when a silver technique is used to visualize the myenteric plexus.     

慢传输型便秘发病机制的研究

慢传输型便秘(STC)的发病机制主要与肠神经系统(ENS)、Cajal间质细胞(ICC)、平滑肌、神经递质等有关。研究发现STC结肠组织中ENS出现退行性变化,肌间神经丛空泡变性,ICC数量减少,形态改变,平滑肌退行性变,多种神经递质发生改变。本文就STC发病机制的研究作一综述。     

Effect of chagas' disease on nitric oxide-containing neurons in severely affected and unaffected intestine

PURPOSE: The pathophysiology of Chagas' disease is incompletely understood. Neuronal nitric oxide has been cited as a candidate neurotransmitter responsible for relaxation of the internal anal sphincter. Neuronal nicotinamide adenine dinucleotide phosphate diaphorase can be used as a marker for neuronal nitric oxide synthase. This study was designed to examine the alterations of the nitric oxidecontaining neurons in the enteric nervous system of the colon of patients who underwent resections for advanced megacolon and to compare these specimens with small-bowel specimens from the same patients and with specimens from control subjects. METHODS: Specimens from resected rectum and extramucosal small-bowel biopsy specimens from 11 patients with Chagas megacolon but no apparent small-bowel clinical involvement were compared with the uninvolved colon and jejunum of 10 control patients with colon cancer. Tissues were fixed in Zamboni solution and evaluated by histochemistry for nicotinamide adenine dinucleotide phosphate diaphorase-containing neurons. Reactivity was evaluated on a 0 to 4 scale in the longitudinal muscle, myenteric plexus, circular muscle, submucosal plexus, and mucosa. RESULTS: Specimens from control patients showed well-stained myenteric and submucosal neurons and an abundant network of terminal nerve fibers in the muscle layers. Chagasic specimens had decreased staining in all layers of the gut. Overall there was a statistically significant decrease in nicotinamide adenine dinucleotide phosphate diaphorase-containing neurons. Biopsy specimens from clinically uninvolved small bowel of patients with Chagas' disease also showed decreased reactivity, but to a lesser degree. CONCLUSIONS: Nicotinamide adenine dinucleotide phosphate diaphorase activity is decreased in patients with advanced megacolon. The alterations are more relevant in the myenteric plexus and the circular muscle. Reactivity is also diminished in the clinically uninvolved small bowel, but to a lesser extent.     

Collagen content and types in the intestinal strictures of Crohn's disease

The collagen content and the relative amount of collagen types were quantitated in control intestine as well as in both inflamed and strictured intestine resected from patients with Crohn's disease. The major collagen type in control intestine was type I (68%), followed by types III (20%) and V (12%). In strictured intestine both collagen content and the relative amount of type V collagen were significantly increased compared with control intestine. Histologic studies demonstrated that in strictured specimens there was a striking proliferation of smooth muscle cells of the muscularis mucosae associated with an accumulation of collagen in the submucosa. The thickness of the muscularis propria was also increased. Immunohistochemical studies demonstrated small amounts of type V collagen in the submucosa of control bowel. In contrast, large amounts of type V collagen were seen in the fibrotic, expanded submucosa of strictured bowel, particularly in the areas where smooth muscle cells of the muscularis mucosae had proliferated. Intestinal strictures in Crohn's disease are therefore characterized by an accumulation of collagen, a proliferation of smooth muscle cells, and an increase in type V collagen, a collagen type produced in relatively large amounts by smooth muscle cells. These changes appear to result in both a loss of the normal compliance of the intestine and a thickening of the intestine wall, resulting ultimately in the intestinal obstruction so frequently seen in patients with Crohn's disease.     

Changes in Muscularis Externa of Rat Small Intestine After Myenteric Ablation with Benzalkonium Chloride: Electron Microscopic and Morphometric Study

The influence of the intrinsic innervation onthe muscularis externa of the rat small intestine wasstudied by chemical ablation of the myenteric plexuswith benzalkonium chloride (BAC). The resulting severe hypertrophy (cell hypertrophy of 96-133% andhyperplasia) differs from working hypertrophy by thedistribution and degree of muscle thickening and bycharacteristics of the extracellular matrix: narrowing of muscle interspaces of 43%; lack of increasedcollagen; changes in the ratio of interstitial cells ofCajal (ICCs) to fibroblasts from 1.6:1 to 0.8:1 with nonumerical decrease in either type of cell; decreased interconnections of ICCs to musclesand nerves due to deformed ICCs; a 197% increase invascularization (capillaries, venules) and lymphatics inboth muscle layers and in the myenteric plexus cleft, possibly initiated by release offibroblast growth factor from myelin fragmentation afternerve damage; and increased macrophages, plasma cells,monocytes and mast cells in the myenteric plexus cleft. These all signify the neural influence on themorphodifferentiation of the muscularis externa inconcert with the extracellular matrixcomponents.     

Hirschsprung's disease and idiopathic megacolon in adults and adolescents

The distinction between Hirschsprung's disease and idiopathic megacolon in childhood dates from the classic clinical, radiological, and histological studies of Bodian, Stephens, and Ward. This article describes clinical experience over 15 years of 94 patients in whom megacolon of these two types was recognised for the first time after the age of 10, to illustrate the problems of diagnosis and treatment in later years. Just as it is now recognised that patients with the clinical characteristics of Hirschsprung's disease may have one of several abnormalities of the myenteric plexus, including not only absence of ganglion cells, but also patchy or zonal loss, abnormal neurones or neuronal dysplasia, so idiopathic megacolon may also be a heterogeneous group of cases. This paper suggests on clinical grounds that those patients with idiopathic megacolon whose symptoms start in childhood differ from those whose symptoms develop in later years.     

Morphology of the developing muscularis externa in the mouse esophagus

Muscularis externa of mouse esophagus is composed of two skeletal muscle layers in the adult. But less attention is paid to the histogenesis of the muscularis externa of the esophagus, and controversies still exist about the developmental process and the spatio–temporal expression characteristics of muscle‐specific proteins during the development of esophageal muscularis externa. To further probe into the developmental pattern of muscularis externa of the mouse esophagus and the expression characteristics of different muscle‐specific proteins, immunohistochemical and terminal deoxyribonucleotidyl transferase‐mediated deoxyuridine triphosphate (dUTP)‐digoxigenin nick‐end labeling apoptotic staining methods are used to investigate the expression patterns of different muscle‐specific proteins and to elucidate the relationship of these protein expressions with the development of muscularis externa of the mouse esophagus. Thus, an understanding of the developing esophageal muscularis externa may be important for developing therapeutic strategies for the treatment of human esophagus diseases. Serial sections of mouse embryos from embryonic day (ED) 12 to ED18, and full‐length esophagi from postnatal first to 5th day were stained with monoclonal antibodies against α‐smooth muscle actin (α‐SMA), α‐sarcomerical actin (α‐SCA), desmin, and monoclonal anti‐skeletal myosin (MHC), while apoptosis was determined using the terminal deoxyribonucleotidyl transferase‐mediated dUTP‐digoxigenin nick‐end labeling assay. The expression of α‐SMA was started at ED12. During the development of ED14–ED15, α‐SMA positive cells were seen extending from the walls of left three, four, and six arch arteries toward the dorsal wall of esophagus. Stronger expression of α‐SCA and desmin could be detected at ED14 and ED15, expression intensity in caudal segment and inner layer was stained stronger than that of cranial segment and outer layer, but after ED16, strong expression of α‐SCA and desmin was found in the outer layer of muscularis externa. Expression of MHC was first detected in the outer layer of cranial segment of muscularis externa at ED17. At ED18, MHC had extended to the level of thyroid gland, staining intensity in the outer layer and cranial segment was stronger than that of inner layer and caudal segment. One to five days after birth, the thickness of the esophageal muscle layer was obviously increased. Most of the muscle cells in the cranial segment of esophagus showed strong expression of α‐SCA and clear cross striations at higher magnification. With progression toward the caudal segment, expression intensity of α‐SCA became weaker, but the expression intensity of desmin was the same at different levels of esophagus. The muscle fibers were arranged densely with high expression of MHC in the cranial segment. During the development of esophageal muscularis externa, few apoptotic cells were observed. α‐SMA, α‐SCA, desmin, and MHC show different expression patterns. The differentiation of outer layer of esophageal muscularis externa is quicker than that of inner layer, and the caudal segment is quicker than that of the cranial segment. Besides, apoptosis may not participate in the development of esophageal muscularis externa. The smooth muscle cells from arch arteries may participate in the development of esophageal muscularis externa.     

Human Defunctionalized Colon (A Histopathological and Pharmacological Study of Muscularis Propria in Resection Specimens)

Despite the regression of diversioncolitis, temporary functional disorders afterbowel continuity restoration could be caused by changesin the smooth muscle of excluded segments; however, studies on the muscularis propria have yieldedcontradictory results. This study was aimed atevaluating possible histopathological changes inmuscular layers and motility of the defunctionalizedhuman colon. Ten patients with defunctionalizedcolorectum (group A) and 10 controls (group B) underwentrestorative or primary resection surgery. Strips weretaken proximal to the colostomy (specimens A1) and the defunctionalized segment (specimens A2),and from the proximal (specimens B1) and distalextremity (specimens B2) of resected colons.Measurements of the thickness of the muscularis propriaand of the volume density of the myenteric plexus, as wellas of spontaneous motility and responses to electricaland pharmacological stimulation were taken. Themuscularis propria was thicker in A2 than in A1specimens (P = 0.004) and in B2 than in B1 specimens (P= 0.007). No differences were recorded either in themyenteric plexus volume density or in colonic motility.No differences were recorded in intergroup comparisons. As no structural or functional changes relatedto defunctionalization were found, clinical disordersafter colorectal restoration could rather result fromunderlying colonic pathology and/or incomplete distal colon resection.