Ultrastructural differences between the anterior and posterior adductors of the strawberry cockle, Fragum unedo.
Adductors of Fragum unedo were observed ultrastructurally and their muscle cells were classified according to the statistically analyzed diameter of their thick myofilaments. Two types of smooth muscle cells were observed in the opaque portion of the anterior adductor: A-type cells containing thick myofilaments of about 46 nm in diameter and B-type cells having 62 nm thick myofilaments. The posterior adductor was also composed of two kinds of cells: the B-type cell, which had thick myofilaments of about 67 nm in diameter, and the C-type, containing thick myofilaments of 90 nm. Two types of oblique-striated cells were commonly recognized in the translucent portions of anterior and posterior adductors. Our observations thus indicate that the posterior adductor generally consists of cells which have thicker myofilaments than the ones of the anterior adductor.
Matsuno
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A
Department of Biology, Faculty of Science, Shimane University, Matsue, Japan.
D000818:Animals; D008974:Mollusca / Q000033:anatomy & histology*; D009130:Muscle, Smooth / Q000166:cytology / Q000648:ultrastructure; D009132:Muscles / Q000166:cytology / Q000648:ultrastructure*