Long term denervation atrophy of the TA muscle in bilaterally sciatectomized rats. H-E stain. A, Normal muscle; B, 1-month, C, 2-month, D, 4-month; E, 8-month; F, 12-month post denervation. Innervated TA muscles are characterized by large, well packed myofiber profiles and minimal intermyofiber spaces. The first stage of TA denervation is characterized by progressive reduction in muscle fiber diameter. In the mid-denervation stage there is a further reduction up to 4-months denervation, in which muscle fiber size is about 10% of normal. Then, the fiber size does not change significantly at least up to 1-year after denervation by bilateral sciatectomy.