Female Reproductive Health: The Reproductive Cycle

In many parts of the world and in some religions today, the topic of menstruation is seen as a taboo, surrounded by silence and shrouded in myths. Many parents hardly discuss the topic with their young girls and women are ashamed talking about their reproductive and menstrual health; but this process is part of our lives and is absolutely normal! In fact, menstruation or a period occurs approximately four hundred and fifty times during a woman’s lifetime. Menstruation is a normal biological process and it shows that we are women. It should be celebrated everyday and not hidden in shame and disgust. It is therefore important that we understand how our bodies work and how this cycle unfolds.

The reproductive cycle also known as the menstrual cycle refers to the regular cyclical changes that occur in the ovaries and uterus making reproduction possible. It consists of two concurrent processes; the ovarian cycle which involves the production of follicles and ovulation and the uterine or menstrual cycle which involves the thickening and shedding of the endometrial lining as a period or menstruation in response to ovarian activities. Periods last for about two to seven days and occur once within a 28-day rotation for an average 28-day cycle. The system occurs on repeat from puberty to menopause, being controlled by hormones, released just at the right time and amount causing menstruation or period to either start or stop during the 28-day rotation. The cycle begins with two ovaries which contains thousands of tiny fluid filled sacs called follicles, each containing one oocyte, an unfertilized egg. At puberty, the ovaries contain about four hundred thousand egg cells or follicles but release one each month resulting in either a pregnancy or a period (menstruation). Before we look at how menstruation occurs, let have a brief overview of the female reproductive system.

Overview of the Female Reproductive System

The female reproductive system consists of the internal and external organs. The Internal Organs include the vagina, cervix, uterus (womb), fallopian (uterine) tubes or oviducts and the ovaries.

The internal organs of the female reproductive system: ovaries, fallopian tubes, uterus, cervix and vagina.

The vagina is a 10cm long fibromuscular tube that connects the uterus to the outside of the body. It receives sperms during sexual intercourse, serves as an outlet for menstrual flow and passage for the baby and other uterine content during childbirth. The vagina also has mucus glands which secretes mucus for lubrication during sexual intercourse to reduce friction between the penis and the vaginal mucosal.

The childbearing organ, the uterus or womb has the size and shape of an inverted pear. It is about 7.5cm long,5cm wide and 2.5cm thick in a female who has never been pregnant. The uterus is divided into an uppermost round portion called fundus, a central portion, the body and a lower narrow portion the cervix which opens into the vagina. The cervix has several mucus glands that help in the production of mucus for lubrication. It prepares the sperms for fertilization and dilates several folds during childbirth to expel the baby. Implantantion of a fertilized egg occurs in the fundus of the uterus. The uterus consists of three layers of tissues, perimetrium which is the outer covering of the uterus that consist of thin layer of epithelial cells, the myometrium, the thickest layer, made up of smooth muscle cells which contracts and relaxes several times during childbirth to propel the fetus outside and the endometrium, the innermost and most active layer of the uterus, which undergoes a series of changes throughout the month under the influence of the hormones, estrogen and progesterone, and is shed during menstruation.

Fertilization occurs in the ampulla . It is also a common site for ectopic pregnancy, that is the fertilized egg implants and grows outside the uterus

The fallopian tubes are 10cm long hollow tubes consisting of four parts; the infundibulum, a funnel shaped portion of the tube to which fingerlike projections called fimbriae are attached. The fimbriae pick up the egg once it is released from the matured follicle in the ovary and sweep it into the tube. The next portion of the tube is the ampulla and it is the widest and longest part of the tube, where fertilization occurs. The fourth part is the isthmus which connects the tube to the uterus.

The ovaries contain ovarian follicles in various growth stages; primary, secondary and graffian follicles, corpus luteum and corpus albicans. 

The ovaries are the female gonads. They produce female gametes or eggs, and female hormones, estrogen and progesterone. The ovaries consist of the ovarian medulla which is made up of dense connective tissues and contains blood and lymphatic vessels and nerves; and the ovarian cortex, which contains ovarian follicles in various stages of development; primary follicles, secondary follicles and matured (graffian) follicle, which after releasing an egg gradually turns into corpus luteum and then into a fibrous scar tissue called corpus albicans.

The external organs of the female reproductive system: the mons pubis, labia majora, labia minora, clitoris, and vulval vestibule

The external organs include the mons pubis, a pad of fatty tissue that cushions the pubic bone and is covered with skin and hair during puberty. From the mons pubis, two folds of skin, labia majora that extend backwards and downward to the perineum and contains oil and sweat glands. It protects the other external organs. Lying inside the labia majora is the labia minora, which surrounds the vaginal and urethral openings. Found at the top of the labia minora is the clitoris, a highly sensitive organ as it contains numerous nerve endings and plays a major role in sexual excitement in females. The vulval vestibule is the region between the labia minora and contains the vaginal and urethral openings.

How Menstruation Occurs

The length of the menstrual cycle varies among women, but the average is to have periods every 28 days. Regular cycles that are longer or shorter than this, from 21 to 40 days, are normal. Periods last about 2-7 days. Ovulation occurs 10-16 days before the start of a period.

Each month, starting from puberty to menopause, a tiny brain organ, the hypothalamus, releases a substance called gonadotrophin releasing hormone(GnRH) which causes the hormone producing organ, the pituitary gland , specifically the anterior pituitary gland, to start releasing two substances, Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH), which causes the ovarian follicles or egg cells to start growing and maturing, causing the follicles to release estrogen. As the follicles grow and estrogen is released into the blood stream, estrogen levels peak signaling the pituitary gland to release less Follicle Stimulating Hormone and more Luteinizing Hormone. This causes the egg cell or follicle that has matured most to what is known as graffian follicle to burst and release an egg and this is known as ovulation which usually happens 10 to 16 days before the start of a period. At the time of ovulation, small amount of blood sometimes leaks into the pelvic cavity from the ruptured follicle, this can cause pain, known as mittelschmerz. The released egg is carried and swept into the fallopian tube by the fimbriae of the tube. The released egg has up to 24 hours for it to be fertilized by a sperm cell, resulting in pregnancy. If this does not happen, the egg’s escapade ends and the window for pregnancy closes for that month.

Menstrual flow from the uterus consists of about 50–150 mL of blood, tissue fluid, mucus, and epithelial cells shed from the endometrium. This discharge occurs because the declining levels of progesterone and estrogens.

Meanwhile, the now empty follicle which gradually turns into corpus luteum starts to release progesterone causing the endometrial lining to thicken and temporary blood vessels, spiral arterioles supplies and enriches the endometrium with blood and nutrients, in preparation for the fertilized egg to embed and grow. If implantation does not occur, that is, if a fertilized egg does not embed, the corpus luteum degenerates to corpus albicans which does not produce hormones. The progesterone and estrogen levels therefore decline, the spiral arterioles collapse and the endometrium degenerates and sloughs off. Blood and tissue leave the body as a period or menstruation. The womb can take about two to seven days to clear its unused content and then the cycle begins again.

Women and their bodies are different and unique, so are their menstrual cycles and that is normal!

Even though this process is cyclical, there are differences among women. Menstruation starts and ends at different times for different women, ovulation occurs at different points in the cycle, some periods lasts longer than others and menarche and menopause occur at different times in life for different women. However, these differences are normal, after all, we’re unique as women and so are our bodies. Appreciating and learning about this monthly process can empower us, giving us the tool to understand and take control of our own bodies.

Ms. Seidu

Picture source: google

Read more

https://ed.ted.com and http://www.osmosis.org