This study describes the gross anatomy of the alimentary tract of Houbara Bustards (Chlamydotis undulata macqueenii), Kori Bustards (Ardeotis kori), Rufous-crested Bustards (Eupodotis ruficrista) and White-bellied Bustards (Eupodotis senegalensis) maintained in captivity by the National Avian Research Center in the United Arab Emirates. The morphology of the alimentary tract and the proportions of each region were similar in all 4 species. The length of the oesophagus, combined proventriculus and ventriculus, small intestine, and large intestine formed 24n2-28n4%, 7n3-9n7%, 40n5-55n1 % and 9n1-14n7 % of the total alimentary tract length respectively. Neither crop nor oesophageal enlargement was observed in the birds examined in this study, although male Kori Bustards possessed a saccus oralis in the oropharyngeal cavity. Oesophagi, proventriculi, ventriculi, caeca and large intestine were well developed in all species. The small intestine was shorter than that of other avian herbivores and granivores when compared on a bodyweight basis. The well differentiated stomachs and well developed caeca of the bustards examined in this study are characteristic of omnivores. Analysis of the mean lengths of the alimentary tract components and weight of the liver and pancreas showed sexual dimorphism in cases where male and female data were available for direct comparison.

S U M M A R Y Type II and III fibrillar collagens were localized by immunogold electron microscopy in resin sections of human femoral articular cartilage taken from the upper radial zone in specimens from patients with osteoarthritis. Tissue samples stabilized by high-pressure cryofixation were processed by freeze-substitution, either in acetone containing osmium or in methanol without chemical fixatives, before embedding in epoxy or Lowicryl resin, respectively. Ultrastructural preservation was superior with osmium-acetone, although it was not possible to localize collagens by this method. In contrast, in tissue prepared by low-temperature methods without chemical fixation, collagens were successfully localized with mono-or polyclonal antibodies to the helical (Types II and III) and aminopropeptide (Type III procollagen) domains of the molecule. Dual localization using secondary antibodies labeled with 5-or 10-nm gold particles demonstrated the presence of Types II and III collagen associated within single periodic banded fibrils. Collagen fibrils in articular cartilage are understood to be heteropolymers mainly of Types II, IX, and XI collagen. Our observations provide further evidence for the complexity of these assemblies, with the potential for interactions between at least 11 distinct collagen types as well as several noncollagenous components of the extracellular matrix.

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We localized Qpe 111 collagen by immunogoldckctron miwscopy iniesin sectiomdintaa normal andmteoarthritic human articular cartilage. Comparisons of antibody s t a bing between tissue prepared by h i g h -p m r e cryofiion and freeze-substitution without fiiatines and that errposed High-pressure cryofintion; Type III collagen; Immunoelectron microscopy; f i m a n cartilage; Osteoarthritis.

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Contractile dysfunctions have been demonstrated in different experimental models of diabetes which have similar characteristics to many of the abnormalities found in the clinical setting. Administration of streptozotocin (STZ) to young adult rats induces beta-cell necrosis of the pancreas which gives rise to hypoinsulinaemia and hyperglycaemia, features which are also seen in untreated type 1 clinical diabetes. We have investigated the chronic effects of STZ-induced diabetes on contraction in rat ventricular myocytes and ultrastructure of cardiac muscle. Diabetes was induced in male Wistar rats (230-270 g) with a single injection of STZ (60 mg kg(-1)). At 2 and 10 months after STZ treatment, the amplitude of contraction was larger in diabetic compared to control myocytes. Time to peak contraction was significantly longer at 2 months but appeared to normalise at 10 months after STZ treatment. In contrast, time to half relaxation of contraction was not significantly different after 2 months but was significantly reduced at 10 months after STZ treatment compared to control. Transmission electron microscope examination of cardiac muscle showed that the ultrastructure of cardiac muscle, especially structures associated with contraction, were not greatly altered after STZ treatment. Sarcomere lengths were not significantly different in papillary or ventricular muscle at 4 or 8 months after STZ treatment compared to control. Our data provide evidence that morphological defects in contractile myofilaments and associated structures cannot explain contractile dysfunctions seen in ventricular myocytes from STZ-treated animals.

Ultrastructural observations were made on myelinated fibers in the tibial nerves in order to investigate the beneficial effects of α‐tocopherol administration in streptozotocin‐diabetic rats. Male Wistar rats, aged 12 weeks and weighing between 250 g to 300 g were studied. Six onset control rats were used to obtain the baseline parameters for this strain and age. Further 3 groups—untreated diabetic animals, diabetic animals treated with α‐tocopherol, and age‐matched controls—were studied over a 3‐month period. In the diabetic animal, administration of α‐tocopherol resulted in a significant increase (p < 0.05) in total plasma vitamin E levels when compared with other groups. Myelinated fiber cross‐sectional area (p < 0.05), axonal area (p < 0.01) and myelin sheath area (p < 0.05) were significantly less in the tibial nerve of diabetic animals than in age‐matched controls, but not different from those of onset controls. In the α‐tocopherol treated diabetic animals, the values for these parameters were intermediate without showing significant difference when compared with age‐matched controls and untreated diabetics. The “g” ratio (axon to fiber area) did not differ between any experimental groups. The number of large myelinated fibers were less in the untreated diabetic animals, but in the α‐tocopherol‐treated diabetics, the values were significantly higher (p < 0.05) than with untreated diabetics and were similar to those of age‐matched controls. In conclusion, this ultrastructural study reiterated the fact that structural abnormalities of myelinated fibers occur in experimental diabetes and that α‐tocopherol administration may be useful in preventing the development of these abnormalities.