Disaggregation of polyribosomes in the spinal anterior horn cells in a patient with X-linked spinal and bulbar muscular atrophy.

The spinal anterior horn cells (AHCs) in a patient with X-linked spinal and bulbar muscular atrophy (SBMA) were examined by light and electron microscopy, giving special attention to alterations in the rough endoplasmic reticulum (ER). Seven age-matched subjects were used as controls. The patient with SBMA showed a severe decrease of AHCs, but the Nissl substance in the remaining AHCs appeared well preserved on light microscopy. Electron microscopy revealed a relatively well preserved parallel lamellar pattern of ER and marked disaggregation of the polyribosomes surrounding the ER in the remaining AHCs. These findings indicate that the Nissl substance was affected in spite of its light microscopic appearance in SBMA, and that the AHCs degenerate through disaggregation of the polyribosomes of the ER.