The female reproductive system is made up of the internal and external sex organs that function in the reproduction of new offspring. In humans, the female reproductive system is immature at birth and develops to maturity at puberty to be able to produce gametes and to carry a fetus to full term. The internal sex organs include the uterus, Fallopian tubes, and ovaries, a pair of oviducts. The external sex organs include the organs of the vulva including the labia, clitoris, and vaginal opening. The vagina is connected to the uterus at the cervix. These systems along with a pair of the mammary glands are integrated structurally and functionally to support the processes of ovulation, pregnancy, birth, and child care.
Ovaries
Ovaries are the primary female sex organ and they are paired organs about four centimeters long and located near the lateral walls of the pelvic cavity on either side of the uterus. They are held in place by ligaments attached to the womb but are not directly attached to the rest of the female reproductive tract.
The reproductive cycle in female primates is called the menstrual cycle. In human females, menstruation is repeated at an average interval of about 28-29 days. The ovaries are small, oval-shaped glands that produce the ovum, and ovarian hormones. 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, with each ovary taking an alternate turn in releasing an egg. A female baby is born with all the eggs that she will ever have. The process by which the egg cell (ovum) is released is called ovulation. Ova are produced from oocyte cells that slowly develop throughout a woman’s early life and reach maturity after puberty. In the ovary, all eggs are initially enclosed in a single layer of cells known as a follicle, which supports the egg. Over time, these eggs begin to mature so that one is released from the ovary in each menstrual cycle. As the eggs mature, the cells in the follicle rapidly divide and the follicle becomes progressively larger. Thus in each month during ovulation, a mature ovum is released. The ovum travels from the ovary to the fallopian tube, where it may be fertilized before reaching the uterus.
As the follicles develop, they produce the hormone oestrogen. Once the egg has been released at ovulation, the empty follicle that is left in the ovary is called the corpus luteum. This then releases the hormones progesterone in a higher amount and oestrogen in a lower amount. These hormones prepare the lining of the uterus for potential pregnancy in the event of the released egg being fertilized. 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 the mother. If the released egg is not fertilized and pregnancy does not occur during a menstrual cycle, the corpus luteum breaks down and the secretion of oestrogen and progesterone stops. Because these hormones are no longer present, the lining of the womb starts to fall away and is removed from the body through menstruation. After menstruation, another cycle begins. The speed of ovulation is periodic and impacts directly to the length of a menstrual cycle.
Fallopian Tubes
Fallopian tubes are narrow tubes that connect between the periphery of each ovary to the uterus. Each fallopian tube is about 10-12 cm in length. It serves as tunnels for the egg cells to travel from the ovaries to the uterus. The fertilization of an egg by sperm takes place in the fallopian tubes and the fertilized egg then moves to the uterus, where it implants into the lining of the uterine wall. The fallopian tubes are consisting of three main parts. The part of the fallopian tube that lies close to the ovary is the funnel-shaped infundibulum. The edges of the infundibulum possess finger-like projections called fimbriae, which help in the collection of the ovum after ovulation. The infundibulum leads to a wider part of the oviduct called the ampulla. In the last part of the viaduct, isthmus has a narrow lumen and it joins to the uterus. The ovum released by the ovary is transported to the junction between isthmus and ampulla of the fallopian tube by the ciliary motion of the inner lining of the fallopian tube. The egg then gets fertilized with the sperm at the ampullary-isthmic junction.
Uterus
The uterus is also called the womb . The uterus sits quite low in the abdomen. The uterus is a single, hollow, muscular, pear-shaped organ located posterior and superior to the urinary bladder. Connected to the two fallopian tubes on its superior end and to the vagina via the cervix on its inferior end. It is supported by ligaments attached to the pelvic wall. The uterus opens onto the vagina through a narrow passage called the cervix. The cavity of the cervix is called the cervical canal along with the vagina forms the birth canal. The wall of the uterus has three layers. The innermost glandular layer is called endometrium that lines the uterine cavity. It is the endometrium that undergoes cyclical changes during the menstrual cycle. The middle thick layer is called the myometrium, it is made up of smooth muscles. Myometrium provides strong contraction during the delivery of the child. The outermost layer is called the membranous perimetrium.
The function of the uterus is to provide nutrition to the fertilized ovum that is developing into a fetus and holding it until the baby is mature enough to be delivered to the outside world. The fertilized ovum gets implanted into the endometrium and gets nourishment from blood vessels which develop exclusively for this purpose. There will be blood vessels in the placenta for providing nutrition as well as oxygen to the fetus and taking away the carbon dioxide and other fetus excretory things. The fertilized ovum becomes an embryo, develops into a fetus, and develops until childbirth in the uterus.
External Organs
The external female genitalia serves the purposes of reproduction and urination. It includes the mons pubis, labia majora, labia minora, clitoris, urethra, vulva vestibule, and vaginal opening. The vagina is the elastic, muscular part of the female genital tract. In humans, it extends from the vulva (the external part of the female genital) to the cervix (the internal part of the female reproductive system that connects the vagina to the uterus). There are usually two external openings in female primates, the urethral opening of the urinary tract, and the vaginal opening of the genital tract. The outer vaginal opening is normally partly covered by a membrane called the hymen. The vagina is for sexual intercourse and birth. It also channels menstrual flow, which occurs as a part of the monthly menstrual cycle.
Mons pubis is a cushion of fatty tissue covered by skin and pubic hair. Labia majora are fleshy fold tissues that extend downward and backward from the mon pubis minor to the perineum. Together with the labia minora, they form the labia of the vulva. Labia minora are paired folds of tissue under the labia majora. The labia is to protect the vagina. The clitoris is a small finger-like structure that lies at the upper junction of the two labia minora and above the urethral opening. Embryologically, the hymen is tended to keep the germs and dirt out of the vagina. It is often torn during first intercourse. However it can also get torn due to other physical activities such as sports, horseback riding, cycling, etc. or even it can get broken by a sudden fall or jolt, insertion of a vaginal tampon, etc. Hence the presence or absence of a hymen is not an indicator of virginity or sexual experience.
Prepared By
Saumya V S
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