Female Reproductive System. Supporting granulosa and theca cells in the growing follicles produce estrogens, until the level of estrogen in the bloodstream is high enough that it triggers negative feedback at the hypothalamus and pituitary. This marks the secretory phase of the menstrual cycle. The back is the dorsal part of the bird between the bases of the wings and from the neck to the tail. The endometrium responds to estrogen released by the follicles during the menstrual cycle and grows thicker with an increase in blood vessels in preparation for pregnancy. In addition to prompting the LH surge, high estrogen levels increase the uterine tube contractions that facilitate the pick-up and transfer of the ovulated oocyte. The muscles of the abdomen protect vital organs underneath and provide structure for the spine. The fimbriae sweep the oocyte into the uterine tube. Typically they work by providing a constant level of both estrogen and progesterone, which negatively feeds back onto the hypothalamus and pituitary, thus preventing the release of FSH and LH. As a result of these large follicles producing large amounts of estrogen, systemic plasma estrogen concentrations increase. The ovaries are located within the pelvic cavity, and are supported by the mesovarium, an extension of the peritoneum that connects the ovaries to the broad ligament. The hymen is a thin membrane that sometimes partially covers the entrance to the vagina. The obstetrical anatomy of a typical female pelvis is best considered as one unit. During the normal hormonal fluctuations in the menstrual cycle, breast tissue responds to changing levels of estrogen and progesterone, which can lead to swelling and breast tenderness in some individuals, especially during the secretory phase. Typically only one follicle, now called the dominant follicle, will survive this reduction in FSH, and this follicle will be the one that releases an oocyte. The major external components of the breasts include the: Internally, the breasts are primarily composed of fat. In contrast, the thicker stratum functionalis layer contains the glandular portion of the lamina propria and the endothelial tissue that lines the uterine lumen. Each ovary is roughly the size of an almond. The … The cycle includes two interrelated processes: oogenesis (the production of female gametes) and folliculogenesis (the growth and development of ovarian follicles). Mutations (changes) in mtDNA occur spontaneously in a somewhat organized pattern at regular intervals in human history. The milk itself exits the breast through the nipple via 15 to 20 lactiferous ducts that open on the surface of the nipple. The ovaries are the female gonads. The oocyte may not enter the tube and may enter the pelvic cavity. Figure 3. As noted earlier, the polar body that results from unequal cell division simply degrades. Get ideas for your own presentations. In folliculogenesis, primordial follicles develop into primary, secondary, and tertiary follicles. Click for a larger image. What specialized structures help guide the oocyte from the ovary into the uterine tube? EM × 1100. Anatomy being the subject of structures is one of the toughest subject. The cilia in the uterine tube promote movement of the oocyte. The results of other hormone replacement studies over the last 50 years, including a 2012 study that followed over 1,000 menopausal women for 10 years, have shown cardiovascular benefits from estrogen and no increased risk for cancer. Once inside, the muscular contractions and beating cilia move the oocyte slowly toward the uterus. This release is ovulation. Keep in mind that most follicles don’t make it to this point. These contractions occur every 4 to 8 seconds, and the result is a coordinated movement that sweeps the surface of the ovary and the pelvic cavity. These women ranged in age from 14 to 59 years and differed in race, ethnicity, and number of sexual partners. Many people consider breasts “accessory organs” to the female reproductive system, as they are responsible for supplying milk to an infant after childbirth. Grey’s Anatomy Recap: A Crisis of Faith This is new territory for Grey’s Anatomy. Although the estrogen in birth control pills does stimulate some thickening of the endometrial wall, it is reduced compared with a normal cycle and is less likely to support implantation. Pap smears sample cells of the cervix, allowing the detection of abnormal cells. … In female it is adapted for child bearing. The Recovery Room: News beyond the pandemic — December 11, Managing diabetes after incarceration: A difficult journey, Low-income Black people in US hit hardest by shutdowns. In a typical 28-day menstrual cycle, ovulation occurs on day 14. Your mtDNA might have a pattern of mutations that aligns more closely with one branch, and your neighbor’s may align with another branch. Research over many years has confirmed that cervical cancer is most often caused by a sexually transmitted infection with human papillomavirus (HPV). The prevalence of cervical cancer in the United States is very low because of regular screening exams called pap smears. When the high-risk types of HPV enter a cell, two viral proteins are used to neutralize proteins that the host cells use as checkpoints in the cell cycle. Read full bio About Betsy Beers: Betsy Beers is the executive producer of "Scandal" and "Grey's Anatomy." When estrogen is lacking, many women find that they suddenly have problems with high cholesterol and the cardiovascular issues that accompany it. Finally, in a non-fertile cycle, the corpus luteum will degrade and menses will occur. Human reproductive system, organ system by which humans reproduce and bear live offspring. The middle section of the uterus is called the body of uterus (or corpus). Once menstrual flow ceases, the endometrium begins to proliferate again, marking the beginning of the proliferative phase of the menstrual cycle. It occurs when the granulosa and theca cells of the tertiary follicles begin to produce increased amounts of estrogen. If a fertilized egg implants in the fallopian tube, doctors call this an ectopic pregnancy. After puberty, it becomes covered in pubic hair. Lactic acid, in combination with other vaginal secretions, makes the vagina a self-cleansing organ. The growth and development of ovarian follicles will be described shortly. The hypothalamus and pituitary gland regulate the ovarian cycle and ovulation. The uterine tubes (also called fallopian tubes or oviducts) serve as the conduit of the oocyte from the ovary to the uterus. However, women in developing countries often do not have access to regular pap smears. Several ligaments maintain the position of the uterus within the abdominopelvic cavity. The larger amount of cytoplasm contained in the female gamete is used to supply the developing zygote with nutrients during the period between fertilization and implantation into the uterus. Over the next 10 to 12 days, the endometrial glands secrete a fluid rich in glycogen. Primordial follicles have only a single flat layer of support cells, called granulosa cells, that surround the oocyte, and they can stay in this resting state for years—some until right before menopause. MNT is the registered trade mark of Healthline Media. The earliest changes occur during the menopausal transition, often referred to as peri-menopause, when a women’s cycle becomes irregular but does not stop entirely. A. Offer a theory as to why endometriosis increases a woman’s risk of infertility. The middle region of the tube, called the ampulla, is where fertilization often occurs. The mons pubis, or public mound, is the fleshy area on the pelvic bone where females typically grow pubic hair. Watch this series of videos to look at the movement of the oocyte through the ovary. FSH stimulates tertiary follicles to grow and granulosa and theca cells begin to produce increased amounts of estrogen. When a baby nurses, or draws milk from the breast, the entire areolar region is taken into the mouth. If pre-cancerous cells are detected, there are several highly effective techniques that are currently in use to remove them before they pose a danger. Special Senses Anatomy and Physiology. The nearby uterine tube, either left or right, receives the oocyte. It has three sections. The ovaries are egg-shaped organs attached to fallopian tubes on the left and right sides of the body. But what happened to the mtDNA of all of the other Homo sapiens females who were living at the time of Eve? This grouping of an oocyte and its supporting cells is called a follicle. Fertilization occurs within the uterine tube, and the final stage of meiosis is completed. 20,5% of male students and %1,8 female students gave an opposition about the “advantage of practical slides for lessons” (p<0,001). The menopausal decrease in inhibin leads to an increase in FSH. Meiosis of a secondary oocyte is completed only if a sperm succeeds in penetrating its barriers. Sperm enter through the vagina, and fertilization of an ovulated oocyte usually occurs in the distal uterine tube. The lobes themselves are surrounded by fat tissue, which determines the size of the breast; breast size differs between individuals and does not affect the amount of milk produced. The cervix is the lower portion of the uterus. Now that we have discussed the maturation of the cohort of tertiary follicles in the ovary, the build-up and then shedding of the endometrial lining in the uterus, and the function of the uterine tubes and vagina, we can put everything together to talk about the three phases of the menstrual cycle—the series of changes in which the uterine lining is shed, rebuilds, and prepares for implantation. The ovarian cycle is a set of predictable changes in a female’s oocytes and ovarian follicles. It is homologous to the If this happens, the HPV infection can influence the cells of the cervix to develop precancerous changes. Unlike spermatogonia, however, oogonia form primary oocytes in the fetal ovary prior to birth. These cilia beat more strongly in response to the high estrogen concentrations that occur around the time of ovulation. The uterus is the muscular organ that nourishes and supports the growing embryo. The hymen is a membrane of tissue that covers the external vaginal opening. The isthmus is the narrow medial end of each uterine tube that is connected to the uterus. The hymen can rupture as a result of pelvic injury, sports activity, pelvic examination, sexual intercourse, or childbirth. As you’ll see next, follicles progress from primordial, to primary, to secondary and tertiary stages prior to ovulation—with the oocyte inside the follicle remaining as a primary oocyte until right before ovulation. Within the growing secondary follicle, the primary oocyte now secretes a thin acellular membrane called the zona pellucida that will play a critical role in fertilization. The risk of developing cervical cancer is doubled with cigarette smoking. During the years leading up to menopause, there is a decrease in the levels of the hormone inhibin, which normally participates in a negative feedback loop to the pituitary to control the production of FSH. The LH surge induces many changes in the dominant follicle, including stimulating the resumption of meiosis of the primary oocyte to a secondary oocyte. It is the stratum functionalis that grows and thickens in response to increased levels of estrogen and progesterone. As a result, endometrial tissue dies and blood, pieces of the endometrial tissue, and white blood cells are shed through the vagina during menstruation, or the menses. Once milk is made in the alveoli, stimulated myoepithelial cells that surround the alveoli contract to push the milk to the lactiferous sinuses. Because of the spontaneous mutations in mtDNA that have occurred over the centuries, researchers can map different “branches” off of the “main trunk” of our mtDNA family tree. If the egg is not fertilized, no signal is sent to extend the life of the corpus luteum, and it degrades, stopping progesterone production. Interestingly, sperm contribute only DNA at fertilization —not cytoplasm. The high estrogen concentrations will eventually lead to a decrease in FSH because of negative feedback, resulting in atresia of all but one of the developing tertiary follicles. Teaching Tolerance provides free resources to educators—teachers, administrators, counselors and other practitioners—who work with children from kindergarten through high school. Oogonia are formed during fetal development, and divide via mitosis, much like spermatogonia in the testis. alveoli: (of the breast) milk-secreting cells in the mammary gland, ampulla: (of the uterine tube) middle portion of the uterine tube in which fertilization often occurs, antrum: fluid-filled chamber that characterizes a mature tertiary (antral) follicle, areola: highly pigmented, circular area surrounding the raised nipple and containing areolar glands that secrete fluid important for lubrication during suckling, Bartholin’s glands: (also, greater vestibular glands) glands that produce a thick mucus that maintains moisture in the vulva area; also referred to as the greater vestibular glands, body of uterus: middle section of the uterus, broad ligament: wide ligament that supports the uterus by attaching laterally to both sides of the uterus and pelvic wall, cervix: elongate inferior end of the uterus where it connects to the vagina, clitoris: (also, glans clitoris) nerve-rich area of the vulva that contributes to sexual sensation during intercourse, corpus albicans: nonfunctional structure remaining in the ovarian stroma following structural and functional regression of the corpus luteum, corpus luteum: transformed follicle after ovulation that secretes progesterone, endometrium: inner lining of the uterus, part of which builds up during the secretory phase of the menstrual cycle and then sheds with menses, fimbriae: fingerlike projections on the distal uterine tubes, follicle: ovarian structure of one oocyte and surrounding granulosa (and later theca) cells, folliculogenesis: development of ovarian follicles from primordial to tertiary under the stimulation of gonadotropins, fundus: (of the uterus) domed portion of the uterus that is superior to the uterine tubes, granulosa cells: supportive cells in the ovarian follicle that produce estrogen, hymen: membrane that covers part of the opening of the vagina, infundibulum: (of the uterine tube) wide, distal portion of the uterine tube terminating in fimbriae, isthmus: narrow, medial portion of the uterine tube that joins the uterus, labia majora: hair-covered folds of skin located behind the mons pubis, labia minora: thin, pigmented, hairless flaps of skin located medial and deep to the labia majora, lactiferous ducts: ducts that connect the mammary glands to the nipple and allow for the transport of milk, lactiferous sinus: area of milk collection between alveoli and lactiferous duct, mammary glands: glands inside the breast that secrete milk, menarche: first menstruation in a pubertal female, menses: shedding of the inner portion of the endometrium out though the vagina; also referred to as menstruation, menses phase: phase of the menstrual cycle in which the endometrial lining is shed, menstrual cycle: approximately 28-day cycle of changes in the uterus consisting of a menses phase, a proliferative phase, and a secretory phase, mons pubis: mound of fatty tissue located at the front of the vulva, myometrium: smooth muscle layer of uterus that allows for uterine contractions during labor and expulsion of menstrual blood, oocyte: cell that results from the division of the oogonium and undergoes meiosis I at the LH surge and meiosis II at fertilization to become a haploid ovum, oogenesis: process by which oogonia divide by mitosis to primary oocytes, which undergo meiosis to produce the secondary oocyte and, upon fertilization, the ovum, oogonia: ovarian stem cells that undergo mitosis during female fetal development to form primary oocytes, ovarian cycle: approximately 28-day cycle of changes in the ovary consisting of a follicular phase and a luteal phase, ovaries: female gonads that produce oocytes and sex steroid hormones (notably estrogen and progesterone), ovulation: release of a secondary oocyte and associated granulosa cells from an ovary, ovum: haploid female gamete resulting from completion of meiosis II at fertilization, perimetrium: outer epithelial layer of uterine wall, polar body: smaller cell produced during the process of meiosis in oogenesis, primary follicles: ovarian follicles with a primary oocyte and one layer of cuboidal granulosa cells, primordial follicles: least developed ovarian follicles that consist of a single oocyte and a single layer of flat (squamous) granulosa cells, proliferative phase: phase of the menstrual cycle in which the endometrium proliferates, rugae: (of the vagina) folds of skin in the vagina that allow it to stretch during intercourse and childbirth, secondary follicles: ovarian follicles with a primary oocyte and multiple layers of granulosa cells, secretory phase: phase of the menstrual cycle in which the endometrium secretes a nutrient-rich fluid in preparation for implantation of an embryo, suspensory ligaments: bands of connective tissue that suspend the breast onto the chest wall by attachment to the overlying dermis, tertiary follicles: (also, antral follicles) ovarian follicles with a primary or secondary oocyte, multiple layers of granulosa cells, and a fully formed antrum, theca cells: estrogen-producing cells in a maturing ovarian follicle, uterine tubes: (also, fallopian tubes or oviducts) ducts that facilitate transport of an ovulated oocyte to the uterus, uterus: muscular hollow organ in which a fertilized egg develops into a fetus, vagina: tunnel-like organ that provides access to the uterus for the insertion of semen and from the uterus for the birth of a baby. The final stages of development of a small cohort of tertiary follicles, ending with ovulation of a secondary oocyte, occur over a course of approximately 28 days. The stratum basalis layer is part of the lamina propria and is adjacent to the myometrium; this layer does not shed during menses. We’ll discuss the production of oocytes in detail shortly. It has three layers: the outer perimetrium, the muscular myometrium, and the inner endometrium. (b) In this electron micrograph of a secondary follicle, the oocyte, theca cells (thecae folliculi), and developing antrum are clearly visible. The external female genitalia are collectively called the vulva. Chinweizu, I. The wall of the uterus is made up of three layers. This is to prepare a nourishing environment for a fetus if pregnancy occurs. Beneath the tunica albuginea is the cortex, or outer portion, of the organ. The switch to positive feedback—which occurs with the elevated estrogen production from the dominant follicle—then stimulates the LH surge that will trigger ovulation. As you look at the house's interi… Prostaglandins will be secreted that cause constriction of the spiral arteries, reducing oxygen supply. Click for a larger image. In a healthy woman, the most predominant type of vaginal bacteria is from the genus Lactobacillus. The following sections discuss these in more detail. Meiosis in the man results in four viable haploid sperm, whereas meiosis in the woman results in a secondary oocyte and, upon completion following fertilization by a sperm, one viable haploid ovum with abundant cytoplasm and up to three polar bodies with little cytoplasm that are destined to die. The correlation of the hormone levels and their effects on the female reproductive system is shown in this timeline of the ovarian and menstrual cycles. Although even these high-risk HPV strains can be cleared from the body over time, infections persist in some individuals. Together, the middle and inner layers allow the expansion of the vagina to accommodate intercourse and childbirth. The walls of the vagina are lined with an outer, fibrous adventitia; a middle layer of smooth muscle; and an inner mucous membrane with transverse folds called rugae. If no pregnancy occurs within approximately 10 to 12 days, the corpus luteum will degrade into the corpus albicans. The labia majora (labia = “lips”; majora = “larger”) are folds of hair-covered skin that begin just posterior to the mons pubis. The dominant follicle produces more estrogen, triggering positive feedback and the LH surge that will induce ovulation. - Anatomy: the study of body structure and relationships among structures - Physiology: the study of body function • Levels of Organization - Chemical level 1. atoms and molecules - Cells 1. the basic unit of all living things - Tissues 1. cells join together to perform a particular function - Organs The mons pubis is a rounded mound of fatty tissue that covers the pubic bone. As the granulosa cells divide, the follicles—now called secondary follicles—increase in diameter, adding a new outer layer of connective tissue, blood vessels, and theca cells—cells that work with the granulosa cells to produce estrogens. Structurally, the endometrium consists of two layers: the stratum basalis and the stratum functionalis (the basal and functional layers). Myometrium ; this layer does not occur, sperm contribute only DNA fertilization. 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