Final answer:
During the development of a Graafian follicle, the antrum increases in size and eventually causes the follicle to rupture at ovulation, releasing the secondary oocyte. Most growing follicles will undergo atresia, with only the dominant one reaching full maturity. After ovulation, the remaining cells in the ruptured follicle form the corpus luteum.
Step-by-step explanation:
As a follicle develops into the Graafian follicle, the antrum continues to increase in size until it causes the follicle to burst at ovulation. The follicles on the surface of the ovary start growing in preparation for ovulation, and during this process, follicles that reach the tertiary stage, also known as antral or tertiary follicles, are characterized by a large and fully formed antrum. However, most of these follicles will undergo a process called atresia, where they degenerate and cease to develop. The one follicle that avoids atresia continues to grow and develop until it reaches maturity, at which point it ruptures during ovulation, releasing the secondary oocyte surrounded by several layers of granulosa cells from the ovary. After the rupture of the mature follicle, the cells that remain in the follicle develop into the corpus luteum, which is an important structure in the luteal phase of the menstrual cycle. The corpus luteum secretes progesterone, which prepares the endometrium for a potential pregnancy. If fertilization does not occur, the corpus luteum degenerates.