Smooth Muscle—Urinary Bladder

The structural units of the smooth muscle consist of spindle-shaped  “smooth” cells of different lengths. “Smooth” means that the cells do not show striation. Basis for their contractility is the presence of myofibrils in the cytoplasmic matrix (sarcoplasm). It is difficult to show the cross-striation of these myofibrils in light microscopic images. If visible at all,  the cross-striation is rendered barely visible as faint pattern in transverse cuts  or as small dots in cross-sections. The delicately structured rod-shaped nucleus is always in a central position. This figure shows the spindle-shaped smooth muscle cells in the wall of a urinary bladder from a frog. Outside the focal plane, a vessel shows Y-like branching.  Whole-mount preparation.

Stain: hematoxylin-eosin; magnification: × 200

References

Kuehnel, W.(2003). Color Atlas of Cytology, Histology, and Microscopic Anatomy. 4^th edition . Institute of Anatomy Universitätzu Luebeck Luebeck, Germany . Thieme Stuttgar t · New York .