Question

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

Answer 1

Progesterone; a hormone of female reproductive cycle is basically secreted by ovaries.
Progesterone is not at all an ovum, neither released nor mature. As mentioned earlier, it is a hormone.

Explanation:

For making your concepts clear we have to take an over veiw of Female reproductive cycle(Menstural cycle):
Stages of female reproductive cycle

Follicular Phase:

• Pituitary gland releases FSH(follicle stimulating hormone) at the start of puberty.
• This hormone stimulates the development of several primary follicles.
• Only one of these follicles contionue to grow with its primary oocyte.
• The remaining follicles break down by degenrative process called follicle atresia.

Uterine Phase:

• FSH stimulates the ovary to produce estrogen hormone.

• Estrogen stimulates the endometrium(inner wall of ovary) and vascularizes it.

• High level of estrogen inhibits the secretion of FSH from pituitary gland.

Ovulation:

• Decrease of FSH and increase of estrogen stimulates the pituitary gland to secrete luteinising hormone(LH).

• Luteinising hormone induces ovulation(discharge of ovum from follicle).

Luteinisation:

• The follicle cells ruptured in follicle atresia form a specil structure called corpus luteum. It is a yellowish grandular structure.
• It start secreting progesterone.
• Progesterone further develops the endometrium and make it receptive for the implantation of zygote.

*Now if the fertilization occurs then the implantation of zygote takes place and the female would be pregnant. And if it does not occur then last phase of female reproductive cycle starts i.e mensturation.