An immunohistochemical study of the organization of ganglia and nerve fibres in the mucosa of the porcine intestine.

In order to elucidate the organization of the enteric nervous system in the mucous plexus, wholemounts from six intestinal regions in six pigs were studied by vasoactive intestinal peptide, substance P, nitric oxide synthase and neurofilament proteins immunohistochemistry. The mucous plexus of both large and small intestine contained ganglia and isolated neurons. They were many and comparably larger in the caecum and colon, few in the ileum, and fewer and smaller in the jejunum. The mucous plexus was subdivided into the lamina muscularis mucosae and lamina proprial subplexuses, and based on location the latter was subdivided further in order to clarify their variations with respect to the amount, sizes and shapes of ganglia and neurons, sizes and orientation of nerve strands and immunoreactivities. Ganglia were situated at different topographical levels in the lamina muscularis mucosae subplexus, outer proprial and interglandular proprial meshworks in the lamina proprial subplexus with the majority of ganglia occurring in the outer proprial meshwork. The mucous plexus in the intestine of the pig is thus a ganglionated plexus showing marked segmental variation in the amount of intramucosal ganglia and isolated nerve cells. These new observations, calls for a re-examination of the mucous plexus to elucidate the regulatory mechanisms of importance in mucosal functions and consideration of the mucous plexus in the intestine of the pig to be one of the major ganglionated plexuses.

Neuronal nitric oxide synthase activity is increased during granulomatous inflammation in the colon and caecum of pigs infected with Schistosoma japonicum.

Neuronal nitric oxide is a non-adrenergic non-cholinergic neurotransmitter in the enteric nervous system and plays a role in a variety of enteropathies including Crohn's and Chagas' diseases, ulcerative colitis, diabetes, atrophy and hypertrophy. The content of neuronal nitric oxide synthase (nNOS) in the colon and the caecum from pigs infected with Schistosoma japonicum was studied using immunohistochemical and histochemical staining for nNOS and nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-diaphorase), respectively. In the infected pigs, lightly, moderately and less severely inflamed tissues showed increased nNOS and NADPH-diaphorase activities in nerve cell bodies and nerve fibres in the enteric plexuses compared to control pigs. There was a significant increase in the nerve cell body density of nNOS immunoreactive nerve cell bodies in the inner submucous plexus, outer submucous plexus and in the myenteric plexus. More intensely stained nerve cell bodies and varicosities were observed in tissue from prenatally infected and prenatally infected, postnatally re-infected pigs compared to postnatally infected pigs. However, the latter showed the highest numerical density of nNOS immunoreactive nerve cell bodies. Marked increases were seen in the inner submucous plexus followed by myenteric plexus, inner circular muscle, outer submucous plexus and mucous plexus. However, in very severe inflamed tissues, the number and staining intensity of nerve cell bodies and nerve fibre varicosities were reduced in plexuses located in the lesions with the inner submucous and mucous plexuses being the most affected. There was no staining in the nervous tissue within the eosinophilic cell abscesses and productive granulomas. The apparent alterations in the activities of enzymes responsible for the generation of nitric oxide (NO) show possible alterations in the NO mediated non-adrenergic non-cholinergic reflexes in the enteric nervous tissue. These alterations might contribute to impaired intestinal motility and absorption, and other pathophysiological conditions seen during S. japonicum infections.

Vasoactive intestinal peptide and substance P-like immunoreactivities in the enteric nervous system of the pig correlate with the severity of pathological changes induced by Schistosoma japonicum.

Limited studies have shown that in intestinal schistosomosis, the enteric nervous tissue becomes inflamed, disrupted and destroyed by granulomas and peptides, amines and neurofilaments contents are altered. Therefore, immunoreactivities of vasoactive intestinal peptide and substance P were correlated to pathological lesions in the large intestine from pigs infected with Schistosoma japonicum. Ganglia situated within or near granulomas showed ganglionitis, and necrosis of neurons as well as infiltration by eosinophils, mast cells, lymphocytes, plasma cells, neutrophils and macrophages. The inner submucous and mucous plexuses were the most damaged. In all categories of inflamed areas, the vasoactive intestinal peptide-like immunoreactive was reduced in all plexuses whereas, that of substance P was increased both in the enteric nerve plexuses and enterochromaffin cells in lightly, moderately and severely inflamed tissues. However, both peptides were highly diminished or absent in very severe lesions and areas surrounding schistosome eggs and mature worms laying eggs in the submucosal veins. The alterations of the levels of vasoactive intestinal peptide and substance P were correlated with severity of inflammation. Our observations show alterations of vasoactive intestinal peptide and substance P contents in the local microenvironment in the vasoactive intestinal peptide- and substance P-mediated reflex pathways which regulate intestinal motility, epithelial transport and modulate immunity. These changes could cause alterations in bowel motility, electrolyte and fluid secretion, vascular and immune functions during S. japonicum infections in the pig. This may, therefore, partly play a role in the pathobiology of migration and egress of schistosome eggs as well as influence trapping of eggs in granulomas, and account for diarrhoea, loss of body weight and failure to thrive, which are recorded in schistosomosis.

Lesions of the enteric nervous system and the possible role of mast cells in the pathogenic mechanisms of migration of schistosome eggs in the small intestine of cattle during Schistosoma bovis infection.

The enteric nervous system in the small intestine of cattle during Schistosoma bovis infection was studied by histological stains and immunohistochemical methods. Lesions due to migration of schistosoma eggs were located mainly in the mucous and the submucous layer overlaying the submucous vascular arcades. Granulomas destroyed ganglia, neurons, nerves fibre strands and nerve fibres. Ganglia situated within or near granulomas were infiltrated by mast cells, eosinophils, lymphocytes, globule leukocytes, neutrophils and macrophages. Mast cells were in close contact with degenerating neuronal perikarya. Whereas vasoactive intestinal peptide-like immunoreactivity in the nerves and neurons in the ganglia within and around granulomas was increased, the neurofilament-like immunoreactivity was reduced. Compared to the myenteric and external submucous plexuses, the internal submucous and mucous plexuses were the most damaged. These changes imply reduced functional capacity in the nervous tissue which might cause reduced motility, malabsorption and partly account for the loss of body weight and condition and failure to thrive which occur in schistosomosis. Biotinylated affinity purified swine anti-rabbit and mouse anti-rabbit immunoglobulins reacted nonspecifically with a subset of mast cells. The reaction revealed many mast cells in early forming granulomas and around schistosome egg tracts and infiltration of mast cells into the ganglia of intestinal nerve plexuses. The observation shows a localized, Type I hypersensitivity reaction suggesting for the release of mast cell-derived chemical mediators in the intestinal reaction to trap or evict S. bovis eggs and to cause diarrhoea.

Demonstration of Mycoplasma capricolum subsp. Capripneumoniae and Mycoplasma mycoides subsp. mycoides, small colony type in outbreaks of caprine pleuropneumonia in eastern Tanzania.

An outbreak of caprine pleuropneumonia involving about 1200 goats in the Coast and Morogoro regions of eastern Tanzania is reported. The major clinical findings were severe respiratory distress, fever, mucopurulent nasal discharge and high mortality involving all age groups and both sexes of goats. The morbidity and mortality rates were 45%-90% and 14%-50%, respectively. The principal pathological lesions were confined to the thoracic cavity and comprised hydrothorax and serofibrinous pleuropneumonia. The histopathological features consisted of a necrotizing fibrinous pleuropneumonia characterized by different degrees of vasculitis, and fibrinocellular exudation into the alveolar septae and lumina, and into interlobular septae and pleura. Mycoplasma capricolum subsp. capripneumoniae, Mycoplasma mycoides subsp. mycoides, Small Colony type Mycoplasma ovipneumoniae and Mycoplasma arginini were isolated from some of the examined goats including a case with a sequestrum which yielded Mycoplasma mycoides subsp. mycoides, Small Colony type. This work reports the first description of an outbreak of caprine pleuropneumonia in Tanzania in which M. capripneumoniae and M. mycoides subsp. mycoides, Small Colony type were concurrently isolated.

The topography, architecture and structure of the enteric nervous system in the jejunum and ileum of cattle.

To date, there appear to have been no detailed and clear descriptions of the nerve plexuses and their subdivisions in the intestine of cattle. In this study, the enteric nervous system in the jejunum and ileum of 12 1-y-old calves was examined using neurofilament protein and vasoactive intestinal peptide immunohistochemistry in wholemounts and paraffin sections combined with staining of paraffin and historesin sections with haematoxylin and eosin. The main organisation of the plexuses was similar to that of the pig, horse and man with external and internal submucous plexuses being morphologically distinct, with further subdivisions of the internal submucous plexus into the external and internal subplexuses. However, in contrast to pig, horse and man, the submucous layer was firmly attached to the inner circular muscle layer. The myenteric plexus was well developed with large ganglia, and primary and secondary nerve strands. Its main axis was oriented parallel to the outer longitudinal smooth muscle; large ganglia and primary nerve strands fused to form complex ganglia, and 2 types of tertiary nerve strands were observed. Antibodies to neurofilament proteins and vasoactive intestinal peptide revealed adendritic, pseudouniaxonal or multiaxonal type II neurons only in the myenteric and submucous plexuses. This appears to be the first report of the identification of isolated uniaxonal, multidendritic type IV neurons in the mucous pericryptal plexus. The new information presented here provides further evidence for the existence of anatomical and functional differences between the external and internal submucous plexuses and for supporting the nomenclature proposed earlier.

The organisation of the enteric nervous system in the submucous and mucous layers of the small intestine of the pig studied by VIP and neurofilament protein immunohistochemistry.

The arrangement of the enteric ganglia and nerve fibre plexuses was examined in the submucous and mucous layers and around Peyer's patches of the porcine small intestine to clarify their organisation. Immunohistochemistry of vasoactive intestinal peptide (VIP) and neurofilament proteins in wholemounts, chopped or paraffin sections was used to locate the neural elements. The ganglia of the internal and external submucous plexuses were situated at 2 different topographic locations, being clearly demarcated by the submucosal vascular arcades and differing in neuronal composition. The internal submucous plexus was the only contributor to the plexus surrounding the follicles of Peyer's patches as a continuous mesh of 3 ganglionated nerve subplexuses. VIP-immunoreactive fibres from this mesh innervated the dome. The mucosal plexus, which was subdivided into 4 subunits--the outer proprial, inner proprial, pericryptal and villous plexuses--contained a few solitary neuronal perikarya. Labelling for neurofilament proteins revealed Dogiel types II, IV and VI neurons. The observations reveal several new features in the enteric nervous system of the pig and clarify its nomenclature.

Clinical observations on bovine parasitic otitis in Tanzania.

Between January 1982 and December 1989 more than 5,000 clinical cases of bovine parasitic otitis were examined. Clinical signs were mild in early cases and were characterised by dullness, anorexia and occasional head shaking, but were severe in long standing cases where the major presenting clinical signs were dark brown aural discharges which soiled the hair below and in front of the ear, emaciation, central nervous signs, recumbency and death.