Pupillary membrane

In the fetus, the pupil is closed by a delicate vascular membrane, the membrana pupillaris, which divides the space in which the iris is suspended into two distinct chambers. The vessels of this membrane are partly derived from those of the margin of the iris and partly from those of the capsule of the lens; they have a looped arrangement, and converge toward each other without anastomosing. About the sixth month the membrane begins to disappear by absorption from the center toward the circumference, and at birth only a few fragments are present; in exceptional cases it persists.