Corpus luteum, which translates to ‘yellow body’ in latin, is the remains of the follicle after a woman ovulates. Several follicles develop during the follicular phase of women’s cycle under the influence of Follicle Stimulating Hormone (FSH). Each follicle contains an egg. In a typical cycle only one egg will become mature enough for ovulation. During ovulation the egg bursts from the follicle and travels through the fallopian tube to be implanted in the endometrium for fertilization. Once the egg leaves, we call the follicle the”corpus luteum”. Corpus luteum is the second half of woman’s menstrual cycle which begins right after ovulation and continues until menstruation begins.
The corpus luteum is essential for establishing and maintaining pregnancy in females. The corpus luteum secretes progesterone, which is responsible for the endometrium development and maintenance, respectively.
When egg is not fertilized
- If the egg is not fertilized, the corpus luteum stops secreting progesterone and decays (after approximately 10 days in humans). It then degenerates into a corpus albicans, which is a mass of fibrous scar tissue.
- The uterine lining sloughs off without progesterone and is expelled through the vagina.
When egg is fertilized
- If the egg is fertilized and implantation occurs, the syncytiotrophoblast (derived from trophoblast) cells of the blastocyst secrete the hormone human chorionic gonadotropin (hCG, or a similar hormone in other species) by day 9 post-fertilization.
- Human chorionic gonadotropin signals the corpus luteum to continue progesterone secretion, thereby maintaining the thick lining endometrium of the uterus and providing an area rich in blood vessels in which the zygote(s) can develop. From this point on, the corpus luteum is called the corpus luteum graviditatis.
What is corpus luteum deficiency?
Corpus luteum deficiency, also known as corpus luteum defect, means that the corpus luteum does not produce enough progesterone to allow a pregnancy to develop. Without sufficient progesterone levels, the lining of the uterus will begin to shed. If a woman is pregnant and has low progesterone levels this may result in miscarriage.
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