A sequential morphological study of ovine ceroid-lipofuscinosis showed that brains of affected lambs were normal at birth, grew until four months of age but then atrophied. Laminar necrosis of cerebral cortex was noted at 10 weeks, occurring first in the parietal area, then spreading to involve frontal and occipital areas while the temporal lobe was least and last affected. With progression of the disease, the laminar pattern was lost. Neuronal necrosis was accompanied by a severe astrocytosis. The granular and multilamellar storage cytosomes increased in size with age. Their structure was interpreted as paracrystalline in which repeating molecules of the dominantly stored lipid binding subunit of mitochondrial ATP synthase interact with neutral lipids and phospholipids. Abnormal cytosomes in neurons of lamb fetuses and a neonate were interpreted as early lesions which contained whorls or stacks of bilayered membrane as well as the more complex multilamellar material. The underlying anomaly leading to the storage of the lipid binding subunit of mitochondrial ATPsynthase remains to be defined. However, it is noted that this disease should be regarded as a lipid binding protein proteinosis or alternatively as a proteolipid proteinosis.

Blindness is a feature of the group of storage diseases of children known as the ceroid-lipofuscinoses. Sequential studies in the ovine model, which most resembles the juvenile form of human disease, showed clearly that blindness had two components, a central and a peripheral. Whereas the central component, attributable to neuronal death and atrophy of the cerebral cortex, was responsible for early loss of vision, retinal atrophy was also extremely advanced in terminal stages of the disease. The primary retinal change was one of dystrophy of photoreceptor outer segments which preceded degeneration and necrosis of the photoreceptors cells themselves. Electroretinography showed that there was a progressive loss of a- and b-waves during the course of the disease, but this was preceded by a diminished c-wave which was eventually replaced by a negative potential. However, the pigment epithelium remained functionally (azide responsive) and ultrastructurally intact throughout the study. Loss of brain weight with selective cerebral atrophy also correlated with abnormal behaviour and facial manoeuvres that were interpreted as partial seizures that did not become generalized.

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Five Devon cattle with suspected ceroid-lipofuscinosis and aged between 19 and 39 months of age were humanely slaughtered and subjected to post-mortem examination. There was severe atrophy of the cerebrum, particularly of the occipital cortex. Microscopy also showed severe atrophy of the retina with complete loss of photoreceptor cells, even in the youngest animal examined. Histopathologically the disease was characterised by accumulation of a fluorescent lipopigment in neurones, including those of the retina and a severe astrocytosis. The disease, which is characterised by the accumulation of subunit c of mitochondrial ATP synthase, is similar to that extensively described in South Hampshire sheep except that the retinal lesions were more severe. In contrast, tremors were not noted in the cattle. The clinical history and similarity to the disease in sheep and other species indicated inheritance was as an autosomal recessive trait.

The ocular pathology of mannosidosis was studied in the bovine model. There was wide-spread vacuolation of many cell types including corneal epithelium, Descemet's endothelium, corneal fibroblasts, pigmented cells, lens epithelium, lens fibres, pigment epithelium and all cell types of the neuroretina. On electron-microscopy most vacuoles were seen to be membrane bound vesicles compatible with being secondary lysosomes and similar to those previously described elsewhere in the body. Additional vacuoles were seen due to dilatations between lens epithelial cells and between lens fibres. The cause of lens and corneal opacities seen in human patients is unclear from the present study but are presumably a consequence of the lesions noted.