The corpus luteum secretes :
**Core Concept**
The corpus luteum is a temporary endocrine structure in the female reproductive system that plays a crucial role in maintaining pregnancy by secreting essential hormones. It forms after ovulation, when the ruptured follicle in the ovary transforms into a temporary endocrine gland.
**Why the Correct Answer is Right**
The corpus luteum secretes progesterone, which is essential for preparing the uterine lining for implantation of a fertilized egg. Progesterone levels rise significantly after ovulation, and its secretion is sustained by the corpus luteum until the placenta takes over in early pregnancy. The corpus luteum also secretes estrogen, but progesterone is the primary hormone secreted by this structure.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the corpus luteum does not primarily secrete estrogen; although it does secrete some estrogen, its primary hormone is progesterone.
**Option B:** This option is incorrect because the adrenal glands secrete aldosterone, not the corpus luteum.
**Option C:** This option is incorrect because the pituitary gland secretes luteinizing hormone (LH), which stimulates the corpus luteum to secrete progesterone, but it does not secrete progesterone itself.
**Clinical Pearl / High-Yield Fact**
A key function of the corpus luteum is to maintain pregnancy by secreting progesterone. If the corpus luteum fails to secrete sufficient progesterone, it can lead to luteal phase defect, which may result in early pregnancy loss.
**Correct Answer:** C. Progesterone.