Figure 9.

Egg transportation. A. Two possible mechanisms for egg transportation are described. Cilia directly contact to COCs to transport, or fluid flow generated by ciliary beating transports COCs. The structures of epithelial folds might be involved in transportation. Cilia are shown by green lines. Movements of COCs are described by arrows. Eggs are illustrated as gray circles in COCs. Cumulus cells are also shown by small black filled circles. B. Movements of COCs in ampulla and isthmus are illustrated. Smooth muscle contraction is involved in the forward and backward movements in the ampulla (arrows). In the ampulla, fertilization occurs. Sperms are also shown. The smooth muscle and a luminal epithelium are shown by gray and orange, respectively. Before entering the isthmus, the cumulus cells are removed. In the isthmus, eggs are transported by smooth muscle contraction.