Which hormone does the corpus luteum mainly secrete?

Uttarakhand CHO - 2021

Applied Physiology

Easy

Appeared in: Uttarakhand CHO - 2021

Explanation

The corpus luteum is a temporary endocrine structure formed in the ovary after ovulation.
Its primary and main secretory product is progesterone, which is essential for preparing the uterine lining (endometrium) for implantation of a fertilized egg.
Progesterone induces the secretory phase of the endometrium, making it thick, vascular, and rich in nutrients to support a potential pregnancy.
While it also produces some estrogen, progesterone is secreted in much larger quantities during the luteal phase, making it the principal hormone.

Option A: Luteinizing Hormone (LH) is secreted by the anterior pituitary gland, not the corpus luteum. Its surge triggers ovulation and it is responsible for stimulating the formation and function of the corpus luteum.
Option B: Although the corpus luteum does secrete some estrogen, it is not the main hormone. The primary source of estrogen during the menstrual cycle is the developing ovarian follicle during the follicular phase.
Option D: Follicle-Stimulating Hormone (FSH) is secreted by the anterior pituitary gland. Its primary role is to stimulate the growth and maturation of ovarian follicles at the beginning of the menstrual cycle.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Hormonal function of the corpus luteum as background academic context rather than a clinical decision trigger.
Understanding progesterone's role is fundamental to hormonal contraception (progestin-only pills), which works by thickening cervical mucus and altering the endometrium.
Infertility can sometimes be caused by a 'luteal phase defect,' where the corpus luteum doesn't produce enough progesterone to sustain a pregnancy, leading to early miscarriage. Progesterone supplements are a common treatment.
What if? If fertilization and implantation occur, the embryo secretes human chorionic gonadotropin (hCG). This hormone acts like LH, stimulating the corpus luteum to continue producing high levels of progesterone, thus preventing menstruation and maintaining the pregnancy until the placenta takes over.

How to Approach the Question

First, identify the core subject of the question: the function of the 'corpus luteum'.
Next, note the keyword 'mainly'. This implies the corpus luteum might secrete more than one hormone, but the question asks for the primary one.
Recall the phases of the menstrual cycle. The corpus luteum is dominant during the luteal phase, which follows ovulation.
Differentiate between hormones produced by the ovaries (estrogen, progesterone) and those produced by the pituitary gland (LH, FSH). This eliminates LH and FSH as options.
Between estrogen and progesterone, recall that progesterone's primary role is to prepare the uterus for pregnancy, which is the main function of the luteal phase. Therefore, progesterone is the main hormone of the corpus luteum.

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