Mitochondrial Inclusion Bodies (Intracytoplasmic Acidophilic Droplets) in Neurons of Chicken Spinal Cords Increase with Age

We studied the pathologic features of neurons that contain intracytoplasmic acidophilic droplets (IADs) in chicken spinal cords. The IADs were lustrous spheroid bodies scattered in the cytoplasm of neurons, variable in size, and protein-rich bodies stained eosinophilic with hematoxylin-eosin, acidophilic with Azan, blue indigo with phosphotungstic acid hematoxylin, and yellow-green with Elastica van Gieson stain histopathologically. Ultrastructurally, almost all IADs were observed as homogeneous highly electron-dense spheroid bodies enclosed by double-limited membranes. Small IADs were observed in mitochondria. Anatomically, IAD-CNs were observed only in the ventral horn of the spinal cord between the fourth sacral and third lumbal vertebrae, and they were particularly frequent in the third sacral vertebrae. Their appearance and accumulative amount were likely to increase with age, while the clinical and pathologic significances of IAD-CNs remain unclear.