PMC5471745_01
Dorsal view of skull, crown removed. Vertical line indicates normal orientation of midline. Here, there is marked lateral deviation of the foramen magnum and occipital condyles.
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F1
Upon dissection of the skull and spinal column, both occipital condyles were found to be markedly distorted, asymmetrical, and deviated to the right (Fig. 1).
CT-scan of skull (ventral aspect). Both condyles are asymmetrical, irregular, and deviated to the right.
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F2
Cross section of cervical spinal cord at the level of the foramen magnum; (4-week-old Jacob lamb with occipital condyle dysplasia,) 5  deviation of the ventral fissure from the midline and marked vacuolation of white matter in the ventral and lateral funiculi, inset; Wallerian degeneration seen as dilated myelin sheets containing spheroids (arrow) and microglia (arrow head), H&E.
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F3
The ventral medial fissure was deviated laterally by approximately 5  from the vertical in cross-section (Fig. 3). Low numbers of myelin sheaths contained one or more microglia with moderate amounts of eosinophilic foamy cytoplasm (Fig. 3, inset).
Cross-section of cervical spinal cord at the level of the foramen magnum; (4-week-old Jacob lamb with occipital condylar dysplasia). On Luxol fast blue stain, myelin fibres appear blue, neuropil appears pink and nerve cells appear purple. Marked loss of myelin in white matter in the ventral and lateral funiculi. Inset; dilated myelin sheaths contain no myelin or only little clumped remnants of myelin (arrowheads). Luxol Fast Blue.
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F4
Marked loss of myelin in these areas was seen on Luxol fast blue stain (Fig. 4).