A simple and rapid method for staining the enteric ganglia: application for Hirschsprung's disease

Morphological and quantitative study of the myenteric plexus in the human tenia coli

The longitudinal muscle in the large intestine in humans and some other mammalian species is concentrated in regions known as "tenia coli." The myenteric plexus under the tenia is believed to be highly developed to control the adjacent large muscle mass, however, data on the innervation of this region are very scarce. We used whole mount preparations of human colon to characterize the organization of the myenteric plexus under the tenia coli (UT) and compared it with the plexus between the tenia (BT). Using histochemical staining for NADPH diaphorase, we found that the meshwork UT was 50% denser than BT, and that the ganglia UT were 30% wider. The density and size of the NADPH-d positive neurons UT were similar to those of BT. We conclude that the myenteric plexus UT is considerably more developed than BT, and suggest to understand the control of colonic motility, the myenteric plexus UT needs to be further investigated.

Recordings from human myenteric neurons using voltage-sensitive dyes

Voltage-sensitive dye (VSD) imaging became a powerful tool to detect neural activity in the enteric nervous system, including its routine use in submucous neurons in freshly dissected human tissue. However, VSD imaging of human myenteric neurons remained a challenge because of limited visibility of the ganglia and dye accessibility. We describe a protocol to apply VSD for recordings of human myenteric neurons in freshly dissected tissue and myenteric neurons in primary cultures. VSD imaging of guinea-pig myenteric neurons was used for reference. Electrical stimulation of interganglionic fiber tracts and exogenous application of nicotine or elevated KCl solution was used to evoke action potentials. Bath application of the VSDs Annine-6Plus, Di-4-ANEPPS, Di-8-ANEPPQ, Di-4-ANEPPDHQ or Di-8-ANEPPS revealed no neural signals in human tissue although most of these VSD worked in guinea-pig tissue. Unlike methylene blue and FM1-43, 4-Di-2-ASP did not influence spike discharge and was used in human tissue to visualize myenteric ganglia as a prerequisite for targeted intraganglionic VSD application. Of all VSDs, only intraganglionic injection of Di-8-ANEPPS by a volume controlled injector revealed neuronal signals in human tissue. Signal-to-noise ratio increased by addition of dipicrylamine to Di-8-ANEPPS (0.98±0.16 vs. 2.4±0.62). Establishing VSD imaging in primary cultures of human myenteric neurons led to a further improvement of signal-to-noise ratio. This allowed us to routinely record spike discharge after nicotine application. The described protocol enabled reliable VSD recordings from human myenteric neurons but may also be relevant for the use of other fluorescent dyes in human tissues.

Age-related changes in the morphology of the myenteric plexus of the human colon

Aging is believed to affect the structure and function of the enteric nervous system, but little specific information on this topic is available, particularly in humans. The aim of this study was to investigate the effect of age on the structure of myenteric ganglia in the human colon. We examined myenteric ganglia in colonic specimens obtained from 168 patients aged 10 days to 91 years. Nerves were stained in whole mount preparations using the vital fluorescent dye 4-(4-dimethylaminostyryl)-methylpyridinium iodide (4-Di-2-ASP) and other staining methods. Human myenteric ganglia were classified into three types: normal, those containing empty spaces ('cavities') and those containing large nerve fiber bundles. We found a statistically significant increase with age in the proportion of ganglia with cavities. Conversely, there was a decrease with age in the proportion of normal ganglia. The proportion of fiber-containing ganglia did not change with age. These findings indicate that there is an increase with age in the number of abnormally appearing myenteric ganglia in the human colon, which may contribute to the disturbed colonic motility in the aging population.

Multiple myenteric networks in the human appendix

The general histological organization of the appendix, including its innervation, is believed to be generally similar to that of the large intestine. However, several authors described an unusual arrangement of the myenteric ganglia within the appendiceal muscle, but conflicting reports do not allow clear conclusions on this matter. The aim of this work was to examine the appendiceal innervation in detail. The myenteric plexus of the human appendix was examined using sections and whole mount preparations. Human small and large intestines were used for comparison. The nerves were stained using immunohistochemistry, enzyme histochemistry for NADPH-diaphorase, and vital staining with 4-(4-diethylaminostyryl)-methylpyridinium iodide. Appendices from rabbits were also studied. In most cases, the innervation of the external muscle of the appendix consisted of three concentric networks of ganglia. These networks were located both between the circular and longitudinal muscle layers and within them. The middle network made connections with the other two. Such arrangement was not observed in the human small and large intestines. The myenteric plexus in the rabbit appendix displayed a much smaller degree of three-dimensional distribution compared with that of the human appendix. It is concluded that the myenteric plexus in the human appendix consists of several distinct networks, and appears to be unique in comparison with the other parts of the intestine.

Clinicopathologic relationship of hypoganglionosis

BACKGROUND/PURPOSE

Congenital motor dysfunction of the intestine associated with a morphologically abnormal myenteric nervous plexus (MP) is known as Hirschsprung's disease allied disorder (HAD). However, the clinicopathologic features of HAD are not well understood, partially because a standardized method of histologic evaluation of MP has not been established. To elucidate the clinicopathologic relationship of HAD the authors reviewed 6 cases of HAD using a newly devised histologic evaluation method.

METHODS

Flat-mounted frozen sections of the ileum were stained for S-100 protein by fluorescent immunohistochemistry. Quantitative evaluation of MP was performed by measuring the fluorescence-positive area (MP ratio), and the results were compared with those of age-matched normal controls.

RESULTS

All of 6 patients required laparotomy within 1 month after birth and enterostomy between 23 days and 10 months. Three died of intractable enteritis by the age of 2.2 years and were totally dependent on parenteral nutrition (PN) throughout their lives. The other 3 have survived for 6 to 10 years but have required PN occasionally. MP ratio in controls was more than 0.34 at all ages, whereas that in HAD was significantly lower than that in controls according to the clinical severity.

CONCLUSION

MP size measured on 2-dimensional demonstration is suggested to be an indicator of clinical severity of HAD. J Pediatr Surg 36:898-900.

Hirschsprung disease and other enteric dysganglionoses

Hirschsprung disease has become a paradigm for multigene disorders because the same basic phenotype is associated with mutations in at least seven distinct genes. As such, the condition poses distinct challenges for clinicians, patients, diagnostic pathologists, and basic scientists, who must cope with the implications of this genetic complexity to comprehend the pathogenesis of the disorder and effectively manage patients. This review focuses on the anatomic pathology, genetics, and pathogenesis of Hirschsprung disease and related conditions. The nature and functions of "Hirschsprung disease genes" are examined in detail and emphasis is placed on the importance of animal models to this field. Where possible, potential uses and limitations of new data concerning molecular genetics and pathogenesis are discussed as they relate to contemporary medical practices.

In vivo fibre optic confocal imaging of microvasculature and nerves in the rat vas deferens and colon

A fluorescence confocal microscopy technique was employed to obtain subsurface images of nerve and microvascular structure in the vas deferens and colon of the living rat. The use of dual labelling with vital dyes and 2-channel confocal acquisition allowed differentiation of microscopic structure at both low and higher magnification. Characteristic staining patterns of nerves and blood vessels were repeatedly obtained in each tissue, suggesting the potential of this technique for studying morphological changes associated with surgical procedures and/or models of neuronal or vascular pathology.

Nitric oxide-containing nerves in bowel segments of patients with Hirschsprung's disease

To assess the role of nerves that synthesize nitric oxide (NO) in Hirschsprung's Disease (HD), the authors studied the distribution of the enzyme NADPH diaphorase (NADPHd) in normal and diseased bowel segments. In the proximal (ganglionic) segment of the colon, NADPHd-positive neurons were present in both myenteric and submucosal plexuses. In the distal involved colonic segments from HD patients, the typical pattern of the neuronal network was completely missing in the regions of the two plexuses; instead, only disorganized NADPHd-positive nerve fibers were present and NADPHd-reactive neurons were absent. Mucosal NO synthase activity was 2.76 +/- 0.38 nmol/g/min in the proximal segment and only 0.83 +/- 0.49 nmol/g/min in the distal segment (P < .05, N = 3).

Two-dimensional demonstration of myenteric nerve plexus: application for pseudo-Hirschsprung's disease

The use of two-dimensional demonstration of myenteric nerve plexus for the morphological estimation of pseudo-Hirschsprung's disease is introduced. By fluorescent immunohistochemistry for S-100 protein on flat-mounted frozen sections, a decrease in the amount of ganglionic plexuses in the small intestinal segments in cases of pseudo-Hirschsprung's disease was able to be distinguished from normoganglionic plexuses in control cases. Moreover, a morphological difference between the two types of cases was clearly demonstrated. This method may be an indispensable tool in the reliable diagnosis of pseudo-Hirschsprung's disease.