Del Castillo J, Anderson M, Smith D S
Proc Natl Acad Sci U S A. 1972 Jul;69(7):1669-72. doi: 10.1073/pnas.69.7.1669.
EACH MUSCLE OF THE SYLLID (ANNELIDA: Polychaeta) proventriculus, the region of the gut posterior to the pharynx, contains a single zigzagging Z band, flanked on each side by a sequence of I-A-H-A-I bands defined by thick (60-90 nm) and thin (5 nm) filaments. The thick filaments show a 14-nm periodicity similar to paramyosin. The muscle cell terminates at the level of the outer I bands. The muscle does not include a complete sarcomere in the strict sense, as defined by a pair of Z bands, but the equivalent H-H distance reaches about 40 mum. Electrophysiological evidence suggests that contraction and relaxation of the cell are, respectively, associated with depolarizing and hyperpolarizing potentials.
多毛纲叶须虫科动物的前胃是肠道中位于咽后方的区域，其每块肌肉都包含一条单一的锯齿状Z带，两侧是由粗（60 - 90纳米）细（5纳米）肌丝界定的一系列I - A - H - A - I带。粗肌丝呈现出与副肌球蛋白相似的14纳米周期性。肌细胞在外周I带水平处终止。严格来说，该肌肉并不包含由一对Z带所定义的完整肌节，但等效的H - H距离约达40微米。电生理证据表明，细胞的收缩和舒张分别与去极化电位和超极化电位相关。
