Smooth Muscle-Duodenum

Smooth muscle cells from the tunica muscularis of the duodenum with inter-spersed actin, myosin and intermediary filaments, pre dominantly actin filaments. There are many small, irregularly distribute d denser areas (dense spots) in the cytoplasm. In conjunction with intermediary filaments, they mediate myofilaments attachment. Note the long oval nuclei in the cell centers. The nuclei of contracted muscle cells are often compressed in the form of a spring. Long, oval, strongly osmiophilic mitochondria 1 , along with microtubules and sparse granular endoplasmic reticulum membranes are found between the filament bundles, mostly in the pole regions. The cell surface exhibits numerous invaginations. These are caveolae, which are considered the equivalents of the T-system in striated muscle fibers. They look similar to pinocytotic vesicles.

1 Mitochondria

Electron microscopy; magnification: × 2500

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 .