top section of a female’s oviduct, a muscular structure whose opening expands like the mouth of a funnel and envelops the mature ovum as it emerges from the ovary; here the oocyte cell undergoes one final division to become a haploid gamete, fertilization by sperm occurs (if available and viable), and the outer layer of the vitelline membrane (extravitelline membrane) surrounds the ovum with its yolk; once this membrane is in place fertilization is impossible because sperm can’t penetrate it; a thin layer of albumen is laid down over the vitelline membrane, including the chalazae, thick twisted strands extending out from both ends of the egg that eventually fuse to the hard shell, suspending the ovum and yolk in the albumen in the center of the egg but allowing to rotate freely so that the embryo always floats to the top above the heavier yolk; Latin infundibulum = funnel