Figure 4. Electron micrographs of rat rectus abdominis muscle fibers from virgin (a), long-term mild diabetic (b), short-term severe diabetic (c), pregnant (d), long-term mild diabetic pregnant (e), and short-term severe diabetic pregnant (f) animals. The micrographs show mitochondria (m), myelin figures (M), well-organized myofibrils forming intact sarcomeres (S) and a system formed by sarcoplasmic reticulum and t tubule-triads (t), areas with disorganized Z lines and thinning sarcomeres (arrows), swollen sarcoplasmic reticulum and dilated T tubes (arrowheads) and areas with disrupted sarcomeres (*). Inset scale bar: 500 nm.