MaleMusFIG 44: Positioning of the sphincter.
A. Epifluorescent image from transgenic animal expressing the egl-15 reporter gene (FGF receptor), lateral right medial plane. The sphincter muscle (sph) and nucleus are proximate to the spicules and rectal gland. (Strain source: C. Branda and M. Stern.)
B. Diagram showing the position of the sphincter muscle in the male tail. (PAG) Pre-anal ganglion.