part_of part of part of develops from develops from neurectodermal cell smooth muscle cell sphincter associated smooth muscle cell smooth muscle cell of sphincter of pupil A circular smooth muscle cell of the iris, innervated by the ciliary nerves (parasympathetic), and acting to contract the pupil. This muscle cell derives from neuroectoderm. This smooth muscle cell results from transformation of epithelial cells to smooth muscle cells. FMA:70611 smooth muscle fiber of sphincter of pupil 2010-09-08T08:53:42Z sphincter pupillae ectoderm-derived structure