Human Anatomy and Physiology - N. I. Fedyukovich 2003

Internal Organs
Urogenital System
Female Reproductive Organs

The FEMALE REPRODUCTIVE Organs (Fig. 85) include the Ovaries and their appendages, the Uterus and uterine tubes, the Vagina, the Clitoris, and the External female genitalia. Depending on their Location, they are classified into internal and external. The female reproductive organs perform not only a reproductive function but also participate in The production of Female Sex Hormones.

Internal female reproductive organs. The Ovary (ovarium) is a paired female gonad located in the pelvic cavity. The mass of the ovary is 5–8 g; its length is 2.5–5.5 cm, width 1.5–3.0 cm, and thickness up to 2 cm. The ovary has an ovoid shape, somewhat compressed in the anteroposterior direction. It is fixed on both sides of the uterus by means of its proper ligament and suspensory ligament. The Peritoneum also participates in fixation, forming the mesovarium (a duplication of the peritoneum) and attaching the ovary to the broad ligament of the uterus. Two free surfaces are distinguished in the ovary: the medial surface, facing the pelvic cavity, and the lateral surface, adjacent to the pelvic wall. The surfaces of the ovary transition posteriorly into a convex free (posterior) border, and anteriorly into the mesovarian border, to which the mesovarium is attached.

In the region of the mesovarian border, There is a depression called the hilum of the ovary, through which Blood Vessels and nerves enter and leave the organ. The ovary has an upper tubal extremity, which faces the Uterine tube, and a lower uterine extremity, connected to the uterus by the proper ovarian ligament. This ligament lies between the two layers of the broad ligament of the uterus. The largest ovarian fimbria of the uterine tube is attached to the tubal extremity of the ovary.

The ovaries belong to the group of mobile organs; their topography depends on the position and size of the uterus.

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Fig. 85. External female genitalia:

1 — mons pubis; 2 — anterior labial commissure; 3 — prepuce of the clitoris; 4 — glans clitoridis; 5 — Labia Majora; 6 — paraurethral ducts; 7 — Labia minora; 8 — duct of the greater vestibular gland; 9 — frenulum of the labia; 10 — posterior labial commissure; 11 — anus; 12 — Perineum; 13 — Vestibule of the vagina; 14 — hymen; 15 — vaginal orifice; 16 — vestibule; 17 — external urethral orifice; 18 — frenulum of the clitoris

The surface of the ovary is covered by a single-layered germinal epithelium, beneath which lies a Cytology/practical/45.html">Dense Connective Tissue tunica albuginea. The internal substance (parenchyma) is divided into outer and inner layers. The outer layer of the ovary is called the cortex. It contains A large number of follicles enclosing oocytes. Among them are vesicular ovarian (mature) follicles (Graafian follicles) and maturing primary ovarian follicles. A mature follicle can be 0.5–1.0 cm in size and is covered by a connective tissue capsule consisting of an outer and an inner layer.

The inner layer is adjacent to the granular layer, which forms the cumulus oophorus containing the oocyte (ovum). Inside the mature follicle, there is a cavity containing follicular fluid. As it matures, the ovarian follicle gradually reaches the surface of the organ. Typically, only a single follicle develops over the course of 28–30 days. By means of its Proteolytic Enzymes, it destroys the tunica albuginea of the ovary and, upon rupturing, releases the ovum. This process is called ovulation. Subsequently, the ovum enters the peritoneal cavity, reaches the fimbriae of the tube, and further proceeds into the abdominal ostium of the uterine tube. A depression remains at the site of the ruptured follicle, where the corpus luteum is formed. It produces hormones (lutein, progesterone) that inhibit The Development of new follicles. If Fertilization of the ovum does not occur, the corpus luteum atrophies and disintegrates. Following the Atrophy of the corpus luteum, new follicles begin to mature again. In the event of fertilization, the corpus luteum grows rapidly and persists throughout Pregnancy, performing an endocrine function. Eventually, it is replaced by connective tissue and transforms into the corpus albicans. The sites of ruptured follicles leave marks On the surface of the ovary in the form of depressions and folds, the number of which increases with age.

The uterus is a hollow, unpaired organ where embryonic development and fetal gestation take place. It comprises the fundus—the upper part, the body—the middle section, and the cervix—the lower narrowed part. The narrowed transition of the uterine body into the cervix is called the ISTHMUS OF THE uterus. The lower part of the cervix, which extends into the vaginal cavity, is termed the vaginal portion of the cervix, while the upper part, lying above the vagina, is called the supravaginal portion. The uterine orifice is bounded by anterior and posterior Lips. The posterior lip is thinner than the anterior. The uterus has anterior and posterior surfaces. The anterior surface of the uterus faces the Urinary Bladder and is called the vesical surface, whereas the posterior surface, facing the rectum, is called the intestinal surface.

The dimensions and mass of the uterus vary. In an adult woman, the length of the uterus averages 7–8 cm, and its thickness is 2–3 cm. The mass of the uterus in a nulliparous woman ranges from 40 to 50 g, whereas in a parous woman it reaches 80–90 g. The volume of the uterine cavity is within 4–6 cm³. It is located in the pelvic cavity between the rectum and the urinary bladder.

The uterus is fixed by means of the left and right broad ligaments, which consist of two peritoneal folds (anterior and posterior). The section of the broad ligament adjacent to the ovary is called the mesovarium. The uterus is also supported by the round ligament and the cardinal ligaments of the uterus.

The uterine wall consists of three layers. The superficial layer is represented by the serous coat (perimetrium), which covers almost the entire uterus; the middle layer is the muscular coat (myometrium), formed by inner and outer longitudinal layers and a middle circular layer; and the inner layer is the mucous membrane (endometrium), covered by a single-layered ciliated columnar epithelium. Beneath the peritoneum around the cervix lies the parametrium (parametrial cellular tissue).

The uterus is highly mobile, which depends on THE POSITION OF adjacent organs.

The uterine (fallopian) tube (tuba uterina) is a paired tubular organ 10–12 cm long and 2–4 mm in diameter; it facilitates The transport of the ovum from the ovary to the uterine cavity. The uterine tubes are located on both sides of the uterine fundus; their narrow ends open into the uterine cavity, while their expanded ends open into the peritoneal cavity. Thus, the peritoneal cavity communicates with the uterine cavity via the uterine tubes.

The uterine tube comprises the infundibulum, ampulla, isthmus, and uterine part. The infundibulum features the abdominal ostium of the tube, which terminates in long, narrow fimbriae. The infundibulum is followed by the ampulla of the uterine tube, and further by its narrow part—the isthmus. The latter transitions into the uterine part, which opens into the uterine cavity via the uterine ostium of the tube.

The wall of the uterine tube consists of a mucous membrane lined with a single-layered ciliated columnar epithelium, a muscular coat with inner circular and outer longitudinal layers of smooth Muscle Cells, and a serous coat.

The vagina is an unpaired hollow tubular organ 8–10 cm long with a wall thickness of 3 mm. Its upper end embraces the cervix, while its lower end opens through the urogenital Diaphragm of the pelvis into the vestibule via the vaginal orifice. In a virgin, this orifice is closed by the hymen, a semilunar or perforated membrane that tears during sexual intercourse, after which its remnants atrophy. Anterior to the vagina lie the urinary bladder and Urethra, and posterior to it lies the rectum, with which it is fused by loose and dense connective tissue.

The vagina features anterior and posterior walls that are joined together. Embracing the vaginal portion of the cervix, they form a dome-shaped recess around it known as the vaginal fornix.

The vaginal wall consists of three coats. The outer adventitial coat is represented by loose connective tissue containing elements of muscle and elastic fibers; the middle muscular coat consists predominantly of longitudinally oriented bundles, as well as circularly directed bundles. In the upper part, the muscular coat merges with the musculature of the uterus, whereas inferiorly it becomes sturdier, with its bundles weaving into the perineal Muscles. The inner mucous membrane is lined with stratified squamous epithelium and forms numerous transverse vaginal folds (rugae). On the anterior and posterior walls of the vagina, these folds become higher, forming longitudinal columns of rugae.

Oogenesis is The process of female germ Cell development in the ovary. Primary Female Germ Cells (oogonia) begin to develop During the first months of intrauterine life. Subsequently, oogonia transform into oocytes. By the time of birth, the ovaries of newborn girls contain about 2 million oocytes, which develop into primary oocytes. However, an intensive process of atresia occurs among them as well, significantly reducing their number. By the onset of Puberty, about 500,000 oocytes capable of further division remain. Thereafter, oocytes develop into primordial follicles and then into primary follicles. Secondary follicles appear only after the attainment of sexual maturity.

The secondary follicle continues to grow and transforms into a mature follicle (Graafian follicle). Subsequently, the follicle ruptures, and the ovum is released into the peritoneal cavity. This process is called ovulation.

The female menstrual (sexual) cycle is characterized by periodic Changes in the mucous membrane of the uterus that occur in coordination with the maturation of the ovum in the ovary and ovulation.

The Menstrual cycle consists of two cycles: the ovarian cycle and the uterine cycle. The ovarian cycle is associated with the maturation of the ovum in the ovary. The second cycle is called uterine because all changes occurring in the Structure and function of the uterus are driven by METABOLISM/18.html">The Influence of ovarian sex hormones.

Three phases of changes in the uterine mucous membrane are distinguished during a woman's single menstrual cycle: the menstrual, postmenstrual, and premenstrual phases.

The menstrual phase (endometrial desquamation phase) occurs when fertilization of the egg does not take place. During desquamation, the production of estrogens and progesterone by the corpus luteum decreases. As a result, foci of necrosis—tissue death—and hemorrhages appear in the uterine mucosa. The functional layer of the mucous membrane is shed, and the next menstruation begins. This phase typically lasts 3—4 days, during which 40—50 ml of blood is discharged.

The postmenstrual phase (proliferative phase) follows menstruation and lasts 10—12 days. This phase is closely linked to The Effect of estrogens on the uterine mucosa—hormones produced by a newly developing follicle. Maximum proliferation of the uterine mucosa is observed on days 12—14, coinciding with full follicular maturation and ovulation. During this period, the thickness of the uterine mucosa reaches 3—4 mm.

The premenstrual phase (secretory phase) is crucial in preparing the uterus for pregnancy. Under the influence of gestagens—hormones produced by the ovarian corpus luteum—the Glands of the uterine mucosa become increasingly filled with secretion, nutrients are stored within the cells, and the number of convoluted Blood Vessels increases. At this time, both the uterine mucosa and the woman's body are prepared for the reception and implantation of a fertilized egg.

During pregnancy, the size of the uterus increases, and its shape changes due to myometrial hypertrophy. After childbirth, the uterus returns to its characteristic shape and dimensions.

Menstrual function is regulated through the coordinated activity of a complex neuro-humoral and Reproductive System (Cerebral Cortex, Hypothalamus, hypophysis, ovaries, vagina, uterus, and fallopian tubes).

External female genitalia. These are located in the anterior region of the perineum within the urogenital triangle and comprise the vulva and the clitoris.

The vulva includes the mons pubis, labia majora and minora, vestibule of the vagina, greater and lesser vestibular glands, and the vestibular bulb.

The mons pubis is separated from the abdominal region above by the suprapubic crease, and from the thighs by the hip creases. It is covered with Hair, which also extends to the labia majora. The subcutaneous fat layer is well developed in the region of the mons pubis.

The labia majora are rounded, paired Skin folds measuring 7—8 cm in length and 2—3 cm in width. They bound the urogenital cleft laterally and are connected anteriorly and posteriorly by the anterior and posterior labial commissures. The skin covering the labia majora contains numerous sebaceous and Sweat Glands.

Between the labia majora lie another pair of skin folds—the labia minora. Their anterior ends enclose the clitoris, forming the prepuce and frenulum of the clitoris, while their posterior ends unite to form a transverse fold known as the frenulum of the labia. The space between the labia minora is called the vestibule of the vagina, which contains the external urethral orifice and the vaginal opening.

The clitoris is the homologue of the male corpora cavernosa and consists of paired erectile bodies. It is divided into the body, glans, and crura, which attach to the inferior rami of the pubic bones. Anteriorly, the body of the clitoris narrows and terminates in the glans. The clitoris possesses a dense fibrous tunica albuginea and is covered with skin rich in sensitive nerve endings.

The perineum is a complex of soft Tissues (skin, muscles, fasciae) that closes the pelvic outlet. It occupies an area bounded anteriorly by the inferior margin of the Pubic Symphysis, posteriorly by the tip of the coccyx, and laterally by the inferior rami of the pubic and ischial bones as well as the ischial tuberosities. A line connecting the ischial tuberosities divides the perineum into two triangles: the anterosuperior portion is termed the urogenital region, and the posteroinferior portion is the anal region. Within the urogenital region lies the urogenital diaphragm, while the pelvic diaphragm is located in the anal region.

The urogenital diaphragm and pelvic diaphragm form a musculofascial plate consisting of two muscle layers (superficial and deep) along with associated fasciae.

The SUPERFICIAL MUSCLES OF the urogenital diaphragm include the superficial transverse perineal muscle, ischiocavernosus, and bulbospongiosus. The Deep Muscles of the urogenital diaphragm comprise the deep transverse perineal muscle and the urethral sphincter.

The pelvic diaphragm includes a superficial muscle layer represented by an unpaired muscle—the external anal sphincter, which contracts to constrict (close) the anal opening. The deep Muscles of the pelvic diaphragm consist of two muscles that form the posterior part of the pelvic floor: the levator ani and the coccygeus.

Internally, the pelvic floor is covered by the superior fascial layer of the pelvis, whereas inferiorly the perineum is covered by the superficial subcutaneous fascia and the inferior Fascia of the pelvic diaphragm.

The muscles of the urogenital diaphragm lie between the superior and inferior Fasciae of the urogenital diaphragm, while the muscles of the pelvic diaphragm are situated between the superior and inferior fasciae of the pelvic diaphragm.

The female perineum differs from that of the male. In females, the urogenital diaphragm is broad, traversed by the urethra and vagina; the muscles are somewhat weaker than in males, whereas the fasciae, conversely, are stronger. Muscle bundles of the urethra also encircle the vaginal wall. The perineal body (central tendon of the perineum) is situated between the vagina and the rectum and is composed of tendinous and elastic fibers.

In the perineal region, on either side of the anal opening, lies a paired depression known as the ischioanal (ischiorectal) fossa. This fossa is filled with adipose tissue and Functions as a resilient, elastic cushion.