Exercise 1 Identify the Ovarian Cycle Order the following sequence of events of the ovarian cycle (acknowledgement: these stages would not all be present at one time in an ovary) beginning with #1 in the diagram. Granulosa cells 2 1 3 Antrum Granulosa cells Ovulation (ruptured follicle) Growing follicle Formation of corpus luteum Mature follicle Primary follicle Oocyte Oocyte Cumulus oophorus Ovary Released ovum 5
The Correct Answer and Explanation is:
To order the sequence of events of the ovarian cycle, we need to follow the natural progression of follicular development and ovulation, starting with the earliest stage and ending with ovulation. Based on the diagram and your question, here’s the correct order:
- Primary follicle: This is the earliest stage in follicular development, where the oocyte (egg cell) is surrounded by a layer of granulosa cells. In this stage, the primary follicle has not yet started to mature.
- Growing follicle: As the follicle grows, the granulosa cells proliferate, and the antrum (fluid-filled space) begins to form. The oocyte becomes larger and prepares for the next stage of development.
- Mature follicle: Also known as a Graafian follicle, this is the fully developed follicle, with a large antrum. The oocyte is now ready for ovulation, and the granulosa cells are involved in producing hormones like estrogen.
- Ovulation (ruptured follicle): This is when the mature follicle ruptures, releasing the ovum (egg) into the fallopian tube. Ovulation is triggered by a surge in luteinizing hormone (LH).
- Formation of corpus luteum: After ovulation, the empty follicle transforms into the corpus luteum, which produces progesterone to prepare the uterus for a potential pregnancy. If pregnancy does not occur, the corpus luteum degenerates.
- Released ovum: This refers to the egg that has been released during ovulation.
Summary:
The ovarian cycle begins with the primary follicle, progresses to the growing follicle, and then to the mature follicle. Ovulation follows, leading to the formation of the corpus luteum, and the cycle ends with the released ovum if no pregnancy occurs.
