After ovulation, which hormone is predominantly secreted by the corpus luteum?

• A. Prolactin
• B. Estrogen
• C. Testosterone
• D. Progesterone

Answer: (D)

The main concept is the hormonal role of the corpus luteum after ovulation. Once the follicle releases the egg, it becomes the corpus luteum, and its primary job is to secrete progesterone. This hormone drives the luteal phase by thickening and maintaining the endometrium in a secretory state, preparing the uterus for a possible pregnancy and helping to sustain early pregnancy if fertilization occurs. The corpus luteum does produce some estrogen as well, but progesterone is by far the dominant hormone it releases at this stage. Prolactin comes from the pituitary and supports milk production, not from the corpus luteum. Testosterone is mainly produced in small amounts in the ovaries and adrenals and is not the principal hormone of the luteal phase.