The Corpus luteum is a temporary endocrine gland that is produced by the reminiscence of the Graafian follicle after ovulation. It secretes large amounts of progesterone and also some amounts of estrogen and inhibin A. The progesterone secreted by the Corpus luteum helps in maintaining the endometrium for implantation and pregnancy.
In the absence of fertilisation, the corpus luteum degenerates and another menstrual cycle starts due to the disintegration of the endometrium.
Structure and Development
The Corpus luteum is formed from the fully mature Graafian follicle after ovulation. The size of the corpus luteum in humans ranges from 2 to 5 cm in diameter. It is formed from the follicular cells. Large luteal cells are formed from granulosa cells and the small luteal cells are formed from theca cells.
The Corpus luteum is formed in the luteal phase of the menstrual cycle. The ovarian follicle transforms into the corpus luteum after the release of a secondary oocyte from the fully matured ovarian follicle.
The corpus luteum remains in the ovary, whereas the secondary oocyte goes to the uterus through the fallopian tube. One corpus luteum is formed in each menstrual cycle.
The corpus luteum acts like an endocrine gland and produces progesterone in large amounts. Progesterone is synthesised from cholesterol by both large and small luteal cells.
The main function of the corpus luteum is to maintain the endometrium for implantation and pregnancy. Progesterone is essential for maintaining the endometrium.
In the absence of pregnancy, the corpus luteum disintegrates and stops making progesterone and transforms into corpus albicans after 10-14 days. This leads to endometrium disintegration and menstruation.
During pregnancy, secretion of hCG (human chorionic gonadotropin) signals the corpus luteum to continue secreting progesterone that ensures the maintenance of endometrium.
It also releases some amounts of estrogen and inhibin A. Estrogen inhibits the further secretion of GnRH (gonadotropin-releasing hormone) from the hypothalamus, therefore secretion of FSH and LH is also inhibited from the pituitary gland.
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