. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 452 J. W. SANGER AND J. M. SANGER ratio of sarcoplasmic reticulum weight to cell weight was considered to represent the percent of cross-sectional areas of the cell occupied by sarcoplasmic reticulum. RESULTS Cross-striated adductor The cross-striated muscle cells of the Bermuda scallop, Pecten ziczac, are ribbon- shaped, ranging from to pm (ave. = nm) in thickness and from 3 to 20 ^m (ave. = 10 /urn) in width (Figs. 1, 2). They do not run the entire length of the adductor but are connected via junctions between
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 452 J. W. SANGER AND J. M. SANGER ratio of sarcoplasmic reticulum weight to cell weight was considered to represent the percent of cross-sectional areas of the cell occupied by sarcoplasmic reticulum. RESULTS Cross-striated adductor The cross-striated muscle cells of the Bermuda scallop, Pecten ziczac, are ribbon- shaped, ranging from to pm (ave. = nm) in thickness and from 3 to 20 ^m (ave. = 10 /urn) in width (Figs. 1, 2). They do not run the entire length of the adductor but are connected via junctions between the terminal Z-bands. The junctions are staggered along the length and width of a cell to form interdigitating boundaries similar to those found in the intercalated discs in cardiac muscles. Each cell consists of one myofibril and in some cells an extra sarcomere is inserted laterally creating a vernier effect (Fig. 3). There seems to be only one elongated nucleus per cell and it is located at the periphery of the cell. The sarcoplasmic reticulum is confined to the area just beneath the cell surface and can be observed most clearly in tangential sections cut just below the plasmalemma (Figs. 4, 5). There are no transverse tubules or sarcoplasmic reticulum in the interior of the cell. The sarcoplasmic reticulum consists of two units: flattened vesicles and tubes linking the vesicles to form a closed system. The vesicles are about /urn in width and up to /urn in length and are interlinked by 2-7 tubular elements, all of which have a uniform bore of about 40 nm. Infrequently, one tube terminates in another tube and in a few cases vesicles fuse to each other directly. The sarcoplasmic reticulum vesicles and tubes are scattered all along the surface of the sarcomere with no periodic arrangement at a particular band of the sarcomere. In cross-sections, surface couplings between the vesicles and the cell surface were observed (Fig. 5), but only occasionally were couplings se
Size: 2039px × 1226px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
