Fig. 22. Low-power electron micrograph of longitudinal section of afibrillar type fiber. In section presented here, little tendency to form myofibrils is demonstrated. In addition, the tubular system is not well developed. s, sarcolemma; e, extracellular space; A, A band; m, mitochondrion. O5O4 fixation, original magnification × 7000. (Kroll AJ: Neuroophthalmology 3:47, 1967.)