抄録
The fine structure of the sphincter and dilator of the pupil of the mouse was studied by light and electron microscopy. The sphincter of the pupil is composed of circumferentially-oriented smooth muscle cells. The dilator of the pupil consists of a large number of myoepithelial cells and a small number of completely-differentiated smooth muscle cells containing no melanosomes. Gap junctions and desmosomes are often observed among the muscle cells of both the sphincter and dilator.
