Corpus luteum is the source of secretion of

The correct option is Progesterone.

Step-by-Step Explanation:

1. Understanding the Corpus Luteum:
The corpus luteum is a temporary endocrine structure in female mammals. It develops from an ovarian follicle after the release of a mature egg during ovulation (the luteal phase of the ovarian cycle).

2. Primary Secretory Function:
Once formed, the corpus luteum begins to secrete high levels of steroid hormones, most notably progesterone, along with moderate amounts of estrogen. Progesterone is essential for preparing the body for potential pregnancy.

3. Role of Progesterone:
Progesterone acts on the endometrium (the inner lining of the uterus) to make it secretory, thick, and highly vascularized. This prepares the uterus for the implantation of a fertilized egg (blastocyst) and helps maintain the pregnancy in its early stages.

4. Evaluating the Options:
• LH (Luteinizing Hormone): Secreted by the anterior pituitary gland, not the corpus luteum. It triggers ovulation and stimulates the formation of the corpus luteum.
• Estradiol / Estrogen: While the corpus luteum does secrete some estrogen (primarily estradiol), its primary and most characteristic secretion that defines its main reproductive role is progesterone.
• Progesterone: This is the principal hormone secreted in large quantities by the corpus luteum to support the luteal phase and early pregnancy, making it the most accurate answer.