Question

What structure forms the 'corpus luteum' and at what stage? Name two hormones secreted by it?

Answer 1

The mass of cells formed in an ovary and responsible for the production of progesterone hormone during the period of early pregnancy is known as corpus luteum. The corpus luteum's role depends on whether fertilization occurred or not. Cysts can form in a corpus luteum sometimes which can lead to painful symptoms and these cysts can go away on their own but treatment is required in some cases.

Complete answer:
The corpus luteum is a transitory endocrine structure in female ovaries that produces relatively high quantities of progesterone and moderate quantities of inhibin A estradiol. Corpus luteum is the remains of the ovarian follicle which has released a mature ovum during previous ovulation.
The Graafian follicle is the structure that forms the corpus luteum after ovulation in the luteal phase. This Graafian follicle ruptures over time to release ovum and then transforms into a corpus luteum.
Two hormones secreted by it are: progesterone and relaxing hormones.
The follicular stage after the first meiotic division before ovulation is the graafian follicle. It contains $2N$ haploid oocytes. A large follicular antrum that makes up most of the follicle is the characteristic feature of this stage. Located eccentrically is the secondary oocyte which has undergone the first meiotic division. It is surrounded by a layer of several cells known as the corona radiata and the zona pellucida.

Note:
Progesterone is produced in the corpus luteum until the fetus is producing adequate levels to sustain the pregnancy which usually occurs between ${7^{th}}$ and ${9^{th}}$ weeks of pregnancy. The pregnancy hormone human chorionic gonadotropin or HCG supports and maintains corpus luteum. Decrease in size at around $10$ weeks of pregnancy can be observed in the corpus luteum.