Question

By what is the hormone progesterone secreted? Is it the released ovum or mature ovum in the ovary?

Answer 1

After ovulation, progesterone prepares the endometrium for the possibility of pregnancy. It causes the lining to thicken in preparation for the acceptance of a fertilised egg. It also stops uterine muscle spasms that would cause the body to reject an egg.

Complete solution:
Progesterone is released by the Graffian follicle. It is neither a released or mature ovum but a corpus luteum formed after ovulation.
Female reproductive cycle stages-
1. Follicular Period: At the commencement of puberty, the pituitary gland secretes FSH (follicle stimulating hormone). This hormone promotes the formation of multiple primary follicles. Only one of these follicles continues to develop alongside its primary oocyte. The remaining follicles degenerate through a process known as follicular atresia.
2. Uterine Stage: FSH increases the production of oestrogen hormone by the ovary. Estrogen promotes and vascularizes the endometrium (the inner membrane of the ovary). A high dose of oestrogen reduces pituitary gland FSH secretion.
3. Ovulation: When FSH levels fall and oestrogen levels rise, the pituitary gland is stimulated to release luteinizing hormone (LH). Luteinizing hormone causes ovulation (discharge of ovum from follicle).
4. Luteinisation: The corpus luteum is an unique tissue produced by follicle cells that rupture in follicular atresia. It is a yellowish-colored glandular structure. It starts secreting progesterone.
Progesterone increases endometrial growth and makes it receptive to zygote implantation.

Note:
If fertilization happens, zygote implantation takes place, and the female becomes pregnant. If this does not happen, the final stage of the female reproductive cycle, menstruation, begins.