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The bovine haemal nodes are lymphatic organs with haemal circulation. The blood circulates inside of them through virtual cavities named sinuses. In these sinuses there is passage of cells and particulate materials from parenchyma to sinuses and vice versa. For this passage temporal overtures exist in the sinus walls. The sinus wall is composed of endothelial cells, basal membrane and reticular cells. Our results have demonstrated that type IV collagen was one of the basal membrane constituents in bovine haemal nodes and by this constitution a dynamic equilibrium of the sinus walls was permitted.

Abstract. A young male Bernese mountain dog presented with neurologic abnormalities consisting of nonambulatory tetraparesis, generalized tremors, and depressed mental status. At necropsy only a mild enlargement of the lateral ventricles was seen. The histologic examination revealed the presence of eosinophilic deposits consistent with Rosenthal fibers (RFs) throughout the white matter of the central nervous system. There was also a marked proliferation of abnormally large astrocytes and limited myelin changes. RFs were most prominent in perivascular, subpial, and subependymal areas, where they were perpendicularly located, producing a pallisaded arrangement. Immunohistochemically, RFs were strongly positive for glial fibrillary acidic protein (GFAP), and when they were examined ultrastructurally they appeared as electron-dense amorphous masses located within the processes of astrocytes, most particularly in the perivascular feet. The histologic and immunohistochemical findings of this canine case were consistent with the published neuropathologic descriptions of Alexander disease in humans and in a few dogs, a rare condition that in humans has been shown to be caused by dominant mutations in the GFAP gene.Key words: Alexander disease; Bernese mountain dog; encephalopathy; GFAP; leukodystrophy; Rosenthal fibers; transmission electron microscopy.A 4-month-old male Bernese mountain dog presented to the Hospital Veterinario Rof Codina with a 3-week history of progressive tetraparesis and tremors, particularly of the hind limbs. The dog had been treated with prednisone (Dacortin, Merck Farma y Química, S. A., Barcelona, Spain) at 0.5 mg/kg per os twice a day for 3 days, but it did not respond to the therapy and the condition worsened rapidly. On admission, the neurologic examination revealed nonambulatory tetraparesis, generalized tremors and depressed mental status. Postural reactions were difficult to evaluate because of generalized weakness, but they were considered to be abnormally slow. Spinal cord reflexes were decreased in all 4 limbs, but cranial nerve function and muscle tone were preserved. The laboratory data revealed normal urine and blood values. A multifocal involvement of the central nervous system was suspected, and, therefore, sampling of cerebrospinal fluid (CSF) was performed by cerebellomedullary cisternal puncture. CSF analysis showed 5 cells/ml (reference range, ,8 cells/ml), total protein concentration of 21 mg/dl (reference range, ,25 mg/dl), and absence of neutralizing antibodies against canine distemper virus. Because of the deteriorated neurologic status, and at the request of the owner, the dog was euthanatized, and a complete necropsy was performed.Gross lesions were found only in the brain, with a moderate enlargement of the lateral ventricles. The brain and the cranial portion of the cervical spinal cord were fixed by immersion in 10% buffered formalin, and then representative coronal slices were embedded in paraffin according to standard laboratory procedures.Paraffin sections (4-5 mm...