Corpus luteum secretes progesterone, primarily after ovulation to prepare the uterus for pregnancy and maintain early gestation.

Question Breakdown

This question examines reproductive endocrinology, focusing on progesterone’s ovarian source—a key topic in biochemistry and physiology for life sciences exams like GATE, linking hormonal regulation to gametogenesis.

Option Explanations

• Leydig cells: Found in testes, these interstitial cells produce testosterone under LH stimulation; they secrete minimal progesterone as a steroidogenesis intermediate, not the primary source.​

• Corpus luteum: Correct; post-ovulation, the ruptured Graafian follicle transforms into corpus luteum, secreting high progesterone (up to 30 mg/day) stimulated by LH to thicken endometrium.

• Sertoli cells: Testicular seminiferous tubule cells support spermatogenesis and secrete inhibin/activin/androgen-binding protein; no significant progesterone production.​

• Graafian follicle: Mature ovarian follicle secretes mainly estrogen (estradiol) via granulosa/theca cells pre-ovulation; progesterone rises only post-rupture in corpus luteum.​

Introduction to Progesterone Secretion

Which of the following secretes progesterone hormone? The corpus luteum, formed post-ovulation in ovaries, is the primary source during the luteal phase and early pregnancy. It maintains pregnancy until placental takeover.

Corpus Luteum Function

LH surge triggers ovulation; residual follicle cells luteinize into corpus luteum, expressing enzymes (CYP11A1, HSD3B) to convert cholesterol → pregnenolone → progesterone. Levels peak mid-luteal phase, dropping if no implantation (menstruation).

Sources Comparison

Corpus luteum dominates reproductive progesterone.​

Relevance in Life Sciences

Critical for menstrual cycle studies, fertility treatments (e.g., progesterone supplements), and hormonal signaling in molecular biology curricula.​