Explain the three phases of menstrual cycle along with the changes in uterus, hormone levels and the ovary during menstrual cycle.
Explain the three phases of menstrual cycle along with the changes in uterus, hormone levels and the ovary during menstrual cycle.
Phase 1 - The Follicular Phase This phase begins on Day 1 of the menstrual period and lasts until ovulation. The brain's hypothalamus and pituitary gland send hormone signals that get the ovaries and uterus ready for pregnancy. Through the influence of a rise in follicle stimulating hormone (FSH) during the first days of the cycle, a few ovarian follicles are stimulated. These follicles, which were present at birth and have been developing for the better part of a year in a process known as folliculogenesis, compete with each other for dominance. Under the influence of several hormones, all but one of these follicles will stop growing, while one dominant follicle in the ovary will continue to maturity. The follicle that reaches maturity is called a tertiary, or Graafian follicle, and it forms the ovum.
As they mature, the follicles secrete increasing amounts of estradiol, an estrogen. The estrogens initiate the formation of a new layer of endometrium in the uterus, histologically identified as the proliferative endometrium.
Phase 2 - The Ovulatory Phase This is the key phase in the menstrual cycle. The level of luteinizing hormone (LH) surges during this phase signalling the release of the egg from the follicle into the fallopian tube. The process is known as ovulation and the egg can then be fertilised for up to 24-48 hours. Cervical mucus is most receptive to sperm around this time and a woman has the best chances of conceiving right before and during ovulation.
It is therefore important to accurately identify when a woman is ovulating if trying for a baby, in order to maximise chances of getting pregnant. During this period When a couple has intercourse, the sperms swim through the cervical mucus, into the uterus and along the fallopian tube, where they meet the egg. While millions of sperms are released, only one sperm can fertilize an egg. If fertilization does not occur, the egg passes through the uterus, the uterine lining then breaks down and is shed several days later as the next menstrual cycle begins.
Phase 3 - The Luteal Phase This is the final phase of the menstrual cycle and lasts from the day of ovulation to the last day before the next period. Glands in the lining of the uterus called the endometrium secrete proteins in anticipation of implantation of the fertilised egg (embryo). If implantation does not occur, the endometrium starts to break down and is eventually sloughed off leading to menstruation. The luteal phase derives its name from the follicle that produces the egg which then becomes a functioning gland called the corpus luteum. The corpus luteum produces progesterone which prepares the endometrium.
This phase begins on Day 1 of the menstrual period and lasts until ovulation. The brain's hypothalamus and pituitary gland send hormone signals that get the ovaries and uterus ready for pregnancy. Through the influence of a rise in follicle stimulating hormone (FSH) during the first days of the cycle, a few ovarian follicles are stimulated. These follicles, which were present at birth and have been developing for the better part of a year in a process known as folliculogenesis, compete with each other for dominance. Under the influence of several hormones, all but one of these follicles will stop growing, while one dominant follicle in the ovary will continue to maturity. The follicle that reaches maturity is called a tertiary, or Graafian follicle, and it forms the ovum.
As they mature, the follicles secrete increasing amounts of estradiol, an estrogen. The estrogens initiate the formation of a new layer of endometrium in the uterus, histologically identified as the proliferative endometrium.
Phase 2 - The Ovulatory PhaseThis is the key phase in the menstrual cycle. The level of luteinizing hormone (LH) surges during this phase signalling the release of the egg from the follicle into the fallopian tube. The process is known as ovulation and the egg can then be fertilised for up to 24-48 hours. Cervical mucus is most receptive to sperm around this time and a woman has the best chances of conceiving right before and during ovulation.
It is therefore important to accurately identify when a woman is ovulating if trying for a baby, in order to maximise chances of getting pregnant. During this period When a couple has intercourse, the sperms swim through the cervical mucus, into the uterus and along the fallopian tube, where they meet the egg. While millions of sperms are released, only one sperm can fertilize an egg. If fertilization does not occur, the egg passes through the uterus, the uterine lining then breaks down and is shed several days later as the next menstrual cycle begins.
Phase 3 - The Luteal PhaseThis is the final phase of the menstrual cycle and lasts from the day of ovulation to the last day before the next period. Glands in the lining of the uterus called the endometrium secrete proteins in anticipation of implantation of the fertilised egg (embryo). If implantation does not occur, the endometrium starts to break down and is eventually sloughed off leading to menstruation. The luteal phase derives its name from the follicle that produces the egg which then becomes a functioning gland called the corpus luteum. The corpus luteum produces progesterone which prepares the endometrium.
