Question

muscle cells are spindle shaped, which help in their contraction and expansion

Answer 1

Answer:

Smooth muscle cells are spindle-shaped and have single elongated nuclei. As in cardiac muscle cells, the configuration of the nuclear membranes in smooth muscle cells changes during contraction and relaxation. Smooth muscle cells contain thin (actin) and thick (myosin) contractile filaments as well as cytoskeletal filaments. The thin filaments are the most conspicuous feature of smooth muscle cells. They fill most of the cytoplasm, are easily demonstrable in electron microscopic preparations, are 4–8 nm thick, and insert into condensations of electron-dense material (“dense bodies”) located subjacent to the plasma membranes. The external laminae of smooth muscle cells are well developed, and transport vesicles are numerous along their surfaces.