Which of the following signals the end of the reproductive period in females?

Day 1 starts with the first day of your period. This occurs after hormone levels drop at the end of the previous cycle, signaling blood and tissues lining the uterus (womb) to break down and shed from the body. Bleeding lasts about 5 days.

Usually by Day 7, bleeding has stopped. Leading up to this time, hormones cause fluid-filled pockets called follicles to develop on the ovaries. Each follicle contains an egg.

Between Day 7 and 14, one follicle will continue to develop and reach maturity. The lining of the uterus starts to thicken, waiting for a fertilized egg to implant there. The lining is rich in blood and nutrients.

Around Day 14 (in a 28-day cycle), hormones cause the mature follicle to burst and release an egg from the ovary, a process called ovulation.

Over the next few days, the egg travels down the fallopian tube towards the uterus. If a sperm unites with the egg here, the fertilized egg will continue down the fallopian tube and attach to the lining of the uterus.

If the egg is not fertilized, hormone levels will drop around Day 25. This signals the next menstrual cycle to begin. The egg will break apart and be shed with the next period.

When a young woman reaches puberty, she starts to ovulate. This is when a mature egg or ovum is released from one of the ovaries. The ovaries are the two female reproductive organs found in the pelvis. If the egg is fertilized by a sperm as it travels down the fallopian tube, then pregnancy occurs. The fertilized egg attaches to the lining of the uterus. The placenta then develops. The placenta transfers nutrition and oxygen to the fetus from mother. If the egg does not become fertilized, the lining of the uterus (endometrium) is shed during menstruation. 

The average menstrual cycle lasts 28 days. The cycle starts with the first day of one period and ends with the first day of the next period. The average woman ovulates on day 14. At this time, some women have minor discomfort in their lower abdomen, spotting, or bleeding, while others do not have any symptoms at all.

A woman is generally most likely to get pregnant (fertile) if she has sex a few days before, and during ovulation.

 What is menstruation?

Menstruation is one part of a woman's cycle when the lining of the uterus (endometrium) is shed. This occurs throughout a woman's reproductive life. With each monthly cycle, the endometrium prepares itself to nourish a fetus. Increased levels of estrogen and progesterone help thicken its walls. If fertilization does not occur, the endometrium, along with blood and mucus from the vagina and cervix make up the menstrual flow that leaves the body through the vagina during the period.

When does menstruation start?

On average, a young woman in the U.S. has her first menstrual period at about age 12. This is generally 2 to 3 years after her breasts start to grow. This is also soon after she notices pubic and underarm hair. Stress, strenuous exercise, and diet can affect when a girl first has her period.

The American College of Obstetricians and Gynecologists recommends that a young woman consult her healthcare provider if she has not started to menstruate by the age of 15, or if she has not begun to develop breast buds, pubic hair, or underarm hair by the age of 13.

How long is a menstrual cycle?

For menstruating women, an average menstrual cycle lasts 28 days. It starts with the first day of the last period and ends with the first day of the next menstrual period. However, the length of women's cycles varies, particularly for the first year or 2 after a young woman has her first period. Women may have cycles as short as 21 days, or as long as 45 days during the first few years. However, anything outside of this range may require medical attention.

The ovaries are a key part of the female reproductive system. Each woman has two ovaries. They are oval in shape, about four centimetres long and lie on either side of the womb (uterus) against the wall of the pelvis. They are held in place by attached to the womb but are not directly attached to the rest of the female reproductive tract, e.g. the .

What do the ovaries do?

The ovaries have two main reproductive functions in the body. They produce oocytes (eggs) for and they produce the reproductive hormones, , progesterone and . The function of the ovaries is controlled by gonadotrophin-releasing hormone (GnRH) released from the hypothalamus which in turn stimulates the pituitary gland to produce luteinising hormone (LH) and follicle stimulating hormone (FSH). These hormones are carried in the bloodstream to the ovary to regulate the menstrual cycle.

The ovaries release an egg (oocyte) at the midway point of each menstrual cycle. Usually, only a single oocyte from one ovary is released during each menstrual cycle, known as . A female baby is born with all the eggs that she will ever have. This is estimated to be around two million, but by the time a girl reaches puberty, this number has decreased to about 400,000. From puberty to the menopause, only about 300 - 400 eggs will be released through ovulation.

The ovarian phases of a 28-day menstrual cycle. Ovulation occurs mid-cycle.

In the ovary, all eggs are initially enclosed in a single layer of cells known as a follicle, which supports the egg. During the follicular phase (first part of the menstrual cycle), one or two ovarian follicles grow due to the action of FSH. As the follicle grows it produces oestradiol. As oestradiol levels rise this induces the hypothalamus and pituitary gland to make high levels of LH (and some FSH) at the midpoint of the cycle to induce ovulation. During ovulation, the egg is released from the follicle in the ovary into the fallopian tube.

Once the egg has been released at ovulation, the empty follicle that remains becomes the corpus luteum (CL). The CL produces the hormones progesterone (in a higher amount) and oestrogen (in a smaller amount). These hormones prepare the lining of the uterus for a potential pregnancy (in the event that the released egg is fertilised by sperm in the female reproductive tract). If the released egg is not fertilised and pregnancy does not occur during a menstrual cycle, the breaks down and the secretion of oestrogen and progesterone stops. Due to the fall in levels of progesterone, the lining of the womb starts to fall away and is lost from the body through , or a ‘period’. Menstruation usually lasts around 3 – 5 days. Day 1 of menstruation signals the start of a new menstrual cycle.

The menopause refers to the ending of a woman's reproductive years following her last menstruation, and is around 51 years of age. This is caused by loss of the remaining follicles in the ovary. When there are no more follicles (which each contain an egg), the ovary also no longer makes the hormones oestrogen and progesterone, which regulate the menstrual cycle. As a result, the occurrence of menstrual cycles and monthly periods ceases.

What hormones do the ovaries produce?

The major hormones secreted by the ovaries are oestrogen and progesterone, both important hormones in the menstrual cycle. Oestrogen production dominates in the first half of the menstrual cycle before ovulation, and progesterone production dominates during the second half of the menstrual cycle after the corpus luteum has formed. Both hormones are important in preparing the lining of the womb for pregnancy and the implantation of a fertilised egg, or . If occurs during a menstrual cycle, the corpus luteum does not lose its ability to function and continues to secrete oestrogen and progesterone, allowing the embryo to implant in the lining of the womb and form a placenta. The ovaries also make small amounts of androgens (male hormones).

What could go wrong with the ovaries?

Any medical conditions that stop the ovaries from functioning properly can decrease a woman's . The ovaries naturally stop functioning at the time of menopause. This occurs in most women around the age of 51 years. If this happens earlier, e.g. before the age of 40 years, it is termed ‘premature ovarian insufficiency’ (previously known as premature ovarian failure). Hormone Replacement therapy (HRT) is the most common treatment to replace the effects of the missing ovarian hormones).

Any abnormality that causes a loss of normal development of the ovaries, such as Turner syndrome, can result in the ovaries not functioning correctly and can result in the loss of a woman's fertility. The ovaries can also be damaged by treatments for other conditions, particularly chemotherapy or radiotherapy for cancer treatment.

The most common disorder of the ovaries is polycystic ovary syndrome, which affects 8–13% of women of childbearing age. In a polycystic ovary, the follicles mature to a certain stage, but then stop growing and fail to release an egg. These stunted follicles can appear as cysts in the ovaries on an (termed ‘polycystic ovarian morphology’). Affected women may have symptoms of excess male hormones (hyperandrogenism), such as excess hair growth (hirsutism) or , or not ovulating (anovulation) leading to irregular (oligomenorrhoea) or absent (amenorrhoea) periods. PCOS can also be associated with a high (), and with insulin not working as efficiently (insulin resistance) leading to an increased risk of type 2 diabetes.

Which of the following signals the end of the reproductive in females?

What signals the end of a menstrual cycle?

What is called the end of reproductive cycle?

What are the 4 phases of the female reproductive cycle?