This increase in estrogen begins to inhibit the secretion of FSH. The fall in FSH allows smaller follicles to die off. They are, in effect, "starved" of FSH. When the level of estrogen is sufficiently high, it produces a sudden release of LH, usually around day thirteen of the cycle.
This LH peak triggers a complex set of events within the follicles that result in the final maturation of the egg and follicular collapse with egg extrusion. Ovulation takes place 28 to 36 hours after the onset of the LH surge and 10 to 12 hours after LH reaches its peak.
The cells in the ovarian follicle that are left behind after ovulation undergo a transformation and become the corpus luteum. In addition to estrogen, they now produce high amounts of progesterone to prepare the lining of the uterus for implantation. The luteal phase, or second half of the menstrual cycle, begins with ovulation and lasts approximately 14 days — typically 12 to 15 days.
During this period, changes occur that will support the fertilized egg, which is called an embryo, should pregnancy result. The hormone responsible for these changes is progesterone, which is manufactured by the corpus luteum. Under the influence of progesterone, the uterus begins to create a highly vascularized bed for a fertilized egg. If a pregnancy occurs, the corpus luteum produces progesterone until about 10 weeks gestation.
Otherwise, if no embryo implants, the circulating levels of hormone decline with the degeneration of the corpus luteum and the shedding of the lining of the uterus endometrium , leading to bleeding. The lining of the uterus, or endometrium, prepares each month for the implantation of an embryo. This preparation occurs under the influence of estrogen and progesterone from the ovary.
If no pregnancy develops, the endometrium is shed as a menstrual period, about fourteen days after ovulation. UCSF Health medical specialists have reviewed this information.
It is for educational purposes only and is not intended to replace the advice of your doctor or other health care provider. We encourage you to discuss any questions or concerns you may have with your provider. Learn the steps of conception and how each works including, sperm transport, egg transport, fertilization and embryo development, and implantation.
About Contact Events News. Search Search. You and Your Hormones. Students Teachers Patients Browse. Human body. Home Hormones Follicle stimulating hormone. Follicle stimulating hormone Follicle stimulating hormone is produced by the pituitary gland.
It regulates the functions of both the ovaries and testes. Lack or insufficiency of it can cause infertility or subfertility both in men and women.
Alternative names for follicle stimulating hormone FSH; follitropin pharmaceutical preparations What is follicle stimulating hormone? How is follicle stimulating hormone controlled? What happens if I have too much follicle stimulating hormone? What happens if I have too little follicle stimulating hormone?
Last reviewed: Feb Prev. Related Glands. Related Endocrine Conditions. Delayed puberty Menopause Polycystic ovary syndrome Turner syndrome Amenorrhoea Premature ovarian failure Female infertility View all Endocrine conditions. Related Hormones. Related Glossary Supplements. In both sexes, LH stimulates secretion of sex steroids from the gonads.
In the testes, LH binds to receptors on Leydig cells, stimulating synthesis and secretion of testosterone.
Theca cells in the ovary respond to LH stimulation by secretion of testosterone, which is converted into estrogen by adjacent granulosa cells. In females, ovulation of mature follicles on the ovary is induced by a large burst of LH secretion known as the preovulatory LH surge.
Residual cells within ovulated follicles proliferate to form corpora lutea, which secrete the steroid hormones progesterone and estradiol. Progesterone is necessary for maintenance of pregnancy, and, in most mammals, LH is required for continued development and function of corpora lutea. The name luteinizing hormone derives from this effect of inducing luteinization of ovarian follicles.
As its name implies, FSH stimulates the maturation of ovarian follicles. Administration of FSH to humans and animals induces "superovulation", or development of more than the usual number of mature follicles and hence, an increased number of mature gametes. FSH is also critical for sperm production. It supports the function of Sertoli cells, which in turn support many aspects of sperm cell maturation. GnRH is a ten amino acid peptide that is synthesized and secreted from hypothalamic neurons and binds to receptors on gonadotrophs.
As depicted in the figure to the right, GnRH stimultes secretion of LH, which in turn stimulates gonadal secretion of the sex steroids testosterone, estrogen and progesterone.
0コメント