Ultrastructural observations on the platelets of the Arabian tahr (Hemitragus jayakari).

The ultrastructure of platelets was studied in specimens of peripheral blood from 18 healthy adult Arabian tahrs (Hemitragus jayakari). The platelets were characterized by their extreme polymorphism. The number of alpha granules, typically one to six per cell, was considerably less than that reported for most animal platelets. Similar to humans, the platelets of the Arabian tahr had nucleoids within the alpha granules. However, nucleoids were not a consistent finding. One or more electron-dense granules, most commonly contained within clear vesicles, was commonly observed. A unique feature was the lack of an open canalicular system, which is considered a hallmark feature of this cell type in most mammalian and reptilian platelets.

Ultrastructural changes in caprine lungs infected with Mycoplasma capricolum subspecies capripneumonia.

Ultrastructural examination of the lungs from goats with natural infections with Mycoplasma capricolum subspecies capripneumonia, the causative agent of contagious caprine pleuropneumonia, revealed extensive hyperplasia of type II pneumocytes. Typically, these type II cells contained abundant numbers of osmiophilic lamellar bodies that had lost most of their characteristic lamellar ultrastructure. These findings were absent in healthy control goats.

Frictional amyloidosis: a study of 10 cases.

Ten patients with macular amyloidosis were studied with particular reference to the role of friction. All 10 patients had a history of prolonged rubbing over a period of 2-5 years with various objects, such as bath sponges, brushes, towels, plant sticks and leaves. The presence of amyloid was confirmed by histochemical stains in six cases and by electron microscopy in four cases. The study confirms the role of friction in the causation of macular amyloidosis and hence, the term 'frictional amyloidosis' aptly describes the condition. The study also emphasizes the need for electron microscopy in the diagnosis of frictional amyloidosis.

Atypical outbreak of caprine cryptosporidiosis in the Sultanate of Oman.

An outbreak of cryptosporidiosis occurred in goats ranging in age from two days to adult, on a well-managed closed farm. None of the other animals on the farm, including sheep, cows and buffalo, were affected. Morbidity approached 100 per cent in goats less than six months of age. Despite intensive supportive care, 238 goats died, ranging in age from two days to over one year. Cryptosporidia were detected in large numbers in the intestinal contents of dead animals and in faecal smears of animals with diarrhoea. Massive numbers of the organisms were also demonstrated histopathologically and by electronmicroscopy, and no other significant pathogens were detected. The outbreak was unique in terms of the extreme virulence of the organism, its apparent species-specificity, and the shedding of the organism by animals over four weeks of age.

Hepatic lipidosis associated with cobalt deficiency in Omani goats.

Livers from 36 of 684 (5.3%) apparently healthy goats examined at an abattoir in the greater Muscat area of Oman exhibited gross pathological findings characterized by extremely pale, friable, fatty livers encompassing the entire organ. Histopathologically, diffuse hepatic lipidosis and occasional bile duct proliferation were observed. Periodic acid Schiff-positive, diastase-resistant pigment was observed in the macrophages lining the sinusoids. These histopathological lesions were consistent with those characteristic of ovine white liver disease. Cobalt analysis revealed that normal livers had six times more cobalt and a 3-fold less fat content than those measured in the fatty livers. This is the first report of an association between cobalt deficiency and hepatic lipidosis in Omani goats.

A cerebral primitive neuroectodermal tumor in a squirrel monkey (Saimiri sciureus).

An adult squirrel monkey with a history of long-term exposure to microwave radiation was found at necropsy to have a malignant tumor of the right cerebral cortex. Gross examination revealed a mass with expanding borders in the right frontoparietal cortex with compression of the adjacent lateral ventricle. Microscopy revealed a tumor composed of sheets of moderate-sized cells, resembling an oligodendroglioma, with clear cytoplasm and central nuclei interrupted by delicate vasculature. Malignant features were present in the form of marked nuclear pleomorphism, frequent mitotic figures, and focal necrosis. A neuronal cell origin for this tumor was supported by immunohistochemical analysis, which revealed immunopositivity for neurofilament proteins and neuron-specific enolase. Staining for vimentin and glial fibrillary acid protein was negative, except in reactive astrocytes at the tumor margins and adjacent to intra-tumoral blood vessels. Antibody activity against Ki-67 antigen, a marker of rapidly proliferating tumor cells, and p53 oncoprotein was strongly positive, indicative of the aggressive and malignant nature of this tumor. The tumor was diagnosed as a cerebral primitive neuroectodermal tumor.

The ultrastructural morphology of the camel eosinophil.

The ultrastructural morphology of the eosinophil was studied in specimens of peripheral blood from normal adult camels and those with eosinophilia. Specific granules were extremely polymorphic. The specific granules exhibited the basic structure of an electron-dense crystalloid core surrounded by a lighter, homogeneous matrix. The crystalloid cores were extremely variable in size and shape, often were segmented and demonstrated a variety of lamellated patterns that were transverse, longitudinal or concentric to the long axis of the core. It was not uncommon to observe multiple crystalloid cores in a single granule. In addition to large specific granules, microgranules and specific microgranules were observed. The extreme polymorphism of the specific granules and variety of lamellated patterns differentiate camel eosinophils from those of other species.

A light and ultrastructural study of rice bodies recovered from a case of date thorn-induced extra-articular synovitis.

Rice bodies are most commonly found in inflammatory joints of patients with rheumatoid arthritis and have traditionally been considered to be a nonspecific response to inflammatory synovial disease. In the present study 18 rice bodies were found in the tibialis tendon sheath of a nine-year-old Omani boy subsequent to a date thorn injury. The rice bodies consisted of three major components: fibrin, collagen, and fibroblasts. In contrast to the findings of other authors there were no type A, B, or C synoviocytes, cartilage, or vascularisation of the rice body. At this extra-articulate site it would appear that rice bodies are composed chiefly of fibrin and that the fibrosis of the rice body occurs as a result of the entrapment of fibroblasts, which subsequently produce collagen. These findings shed doubt on the synovial origin of rice bodies and suggest that rice bodies may have multiple origins, depending on their location. This is the first ultrastructural study of rice bodies associated with a date thorn injury.

Renal hemosiderosis due to thalassemia: a light and electron microscopy study with electron probe X-ray microanalysis.

A kidney biopsy specimen with pronounced hemosiderosis from a patient with beta-thalassemia major was studied by light and electron microscopy, including X-ray microanalysis. Ferritin was absorbed from the glomerular ultrafiltrate through the parietal epithelial cells and the tubular epithelial cells and from the blood through the endothelial cells. It was transported in siderosomes into the surrounding basal lamina, where electron-dense deposits of hemosiderin were found in the outer part of the lamina densa and the reticular lamina. Fibrosis was seen as a reaction to the iron followed by severe atrophy of affected structures.