Histologic Variability of the Canine Neurohypophysis Due to Sectioning Plane Orientation
This study highlights the influence of sectioning plane orientation on the histologic appearance of the canine neurohypophysis in nonclinical toxicity studies. A review of 79 pituitary sections revealed substantial variability in tissue orientation, with angled proximal transverse sections being most common. Increased neurohypophyseal cellularity and vacuolation—often perceived as potential lesions—were more pronounced in sections closer to the third ventricular recess, reaching 100% incidence in sagittal longitudinal sections. Cystic structures were common across most orientations and were the only finding in historical control data, but were not associated with vacuolation or cellularity changes. There may be wide variability in canine pituitary gland sectioning, affecting histologic appearance of otherwise normal histoanatomical features. Standardizing pituitary trimming may reduce variability in interpretation and prevent misidentification of non-lesions.
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