Cell Death Processes of Postovulatory Cumulus Granulosa Cells in the Mouse Oviduct Ampulla after Mating
In order to clarify the elimination process of the granulosa cells and excess spermatozoa in oviduct after ovulation, female reproductive organs of ICR mouse were observed at 3, 5, 8 and 12 hours after mating by immunohistochemistry and electron microscopy. All oviduct ampullas at five hours after two-hour mating contained several oocytes with numerous granulosa cells, and between 5 and 12 hours after mating, the majority of granulosa cells disappeared from the ampullas. At five hours after mating, approximately 5% of granulosa cells were TUNEL-positive and, at eight hours, 30% were TUNEL-positive. Ultrastructurally, there were nuclear changes mainly in compaction and margination of heterochromatin. These were designated as signs of classical apoptosis. In addition, some granulosa cells, approximately 2% at five hours and 13% at eight hours after mating, showed mitochondrial swelling and disruption of cellular, nuclear and organelle membranes. These were designated as typical signs of necrotic cell death. Therefore, postovulatory granulosa cells are eliminated from oviduct ampullas through two different cell death processes, and F4/80-positive macrophages appear after 5-8 hours after mating and remove mainly apoptotic cells.
