Ultrastructural study of the Jimpy mice shows lack of myelin in the central nervous system: low density of glial cells, defect of maturation of oligodendrocytes and deficiency in axonal growth. The lack of myelin is more proeminent in late myelinating structures: corpus callosum and corticospinal fasciculus. Failure in myelin is rather the consequence of an early interruption of myelination as that of demyelination (a destruction of the sheats).
对Jimpy小鼠的超微结构研究显示，其中枢神经系统中缺乏髓磷脂：神经胶质细胞密度低、少突胶质细胞成熟缺陷以及轴突生长不足。髓磷脂缺乏在晚期髓鞘形成结构中更为明显：胼胝体和皮质脊髓束。髓磷脂的缺失更像是髓鞘形成早期中断的结果，而非脱髓鞘（髓鞘的破坏）的结果。
