A 22 year old lady undergoing laparoscopy is noted to have a cyst on her ovary. The cyst is described as a “blister” on the surface of the ovary. Which of the following is this most consistent with?

During initial follicular growth, the oocyte grows larger, granulosa cells increase in number, and a zona pellucida, or protein matrix, forms around the oocyte. The fluid filling the follicler continues to accumulate and the cellular surface of the follicle thins in preparation for ovulation. This process can be seen grossly and has been described as a blister on the ovarian surface.