MICROANATOMY

Detailed explanation-1: -Smooth muscle cells are spindle shaped, have a single, centrally located nucleus, and lack striations. They are called involuntary muscles. Cardiac muscle has branching fibers, one nucleus per cell, striations, and intercalated disks. Its contraction is not under voluntary control.

Detailed explanation-2: -Smooth muscle derives from both mesoderm and neural crest cells; this is because smooth muscle contributes to many different tissues throughout the body. One unique feature of neural crest cells is that their migration occurs during embryological development.

Detailed explanation-3: -Muscle cells are spindle shaped structures that contract and relax allowing the organ to move easily.

Detailed explanation-4: -The spindle shape of the mononucleated smooth muscle cell permits a close contact among cells in the splanchnic and vascular walls.

Detailed explanation-5: -Muscle spindles are proprioceptors that consist of intrafusal muscle fibers enclosed in a sheath (spindle). They run parallel to the extrafusal muscle fibers and act as receptors that provide information on muscle length and the rate of change in muscle length. The spindles are stretched when the muscle lengthens.