Anatomy and Physiology of Children and Adolescents - M. R. Sapin 2007

Genitourinary system
Reproductive system
Female reproductive organs - Internal female reproductive organs

The FEMALE REPRODUCTIVE Organs are divided into internal and external. The Internal female reproductive organs include the Ovaries, uterine tubes, Uterus, and Vagina, all located in the lesser pelvis cavity. The external genitalia comprise the Vestibule of the vagina, the Labia Majora and minora, and the Clitoris (Fig. 67).

The Ovary is a paired ovoid organ. Like the male Testis, it performs two Functions: exocrine and endocrine. As an exocrine gland, the ovary produces ova (egg Cells). Its endocrine function consists of producing and releasing Female Sex Hormones into the bloodstream. The ovary is situated in the lesser pelvis near the lateral pelvic wall, beneath the free end of the Uterine tube.

The ovary has an upper tubal extremity facing the uterine tube and a lower uterine extremity connected to the uterus via the proper ovarian ligament. The upper border of the ovary is attached to its mesentery (Peritoneum), which serves as the hilum of the ovary. Through this upper border, Blood Vessels and nerves enter the organ. The ovary is covered by a single-layered cuboidal (germinal) epithelium, beneath which lies a Connective Tissue capsule known as the tunica albuginea. Underneath the tunica albuginea is the ovarian cortex, consisting of connective tissue that houses numerous young growing follicles (primary), maturing follicles (secondary), as well as follicles undergoing regression (atretic bodies) (Fig. 68). At certain times, the adult female ovary also contains corpora lutea: either menstrual (cyclic) or of Pregnancy.

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Fig. 67. FEMALE Urogenital System:

1 — Kidney; 2 — Ureter; 3 — fundus of uterus; 4 — uterine cavity; 5 — body of uterus; 6 — mesosalpinx; 7 — ampulla of uterine tube; 8 — fimbriae of tube; 9 — broad ligament of uterus (mesometrium); 10 — Urinary Bladder; 11 — mucous membrane of urinary bladder; 12 — ureteric orifice; 13 — crus of clitoris; 14 — body of clitoris; 15 — glans clitoridis; 16 — external urethral orifice; 17 — vaginal orifice; 18 — greater vestibular gland (Bartholin's gland); 19 — bulb of vestibule; 20 — female Urethra; 21 — vagina; 22 — vaginal rugae; 23 — orifice of uterus (external os); 24 — cervical canal; 25 — round ligament of uterus; 26 — ovary; 27 — ovarian follicle; 28 — vesicular appendage; 29 — epoophoron; 30 — tubal folds

The ovarian medulla is formed by connective tissue containing the intra-organ Blood Vessels and NERVES OF THE ovary. Each growing follicle contains an immature oocyte surrounded by a layer of follicular cells that synthesize and secrete female sex hormones—estrogens. A follicle that has reached its maximum development becomes filled with follicular fluid. Such a mature follicle is called a vesicular ovarian follicle (Graafian follicle). It is located directly beneath the tunica albuginea, which thins out at this site. During ovulation (the release of the egg from the ovary), the thinned tunica albuginea ruptures, the follicle bursts, and the oocyte is released into the peritoneal cavity. From the peritoneal cavity, the oocyte enters the nearby abdominal opening of the uterine tube. It then moves along the uterine tube toward the uterine cavity. If the oocyte encounters a spermatozoon within the uterine tube, Fertilization takes place. The fertilized egg travels along the tube into the uterine cavity, where it implants into the mucous membrane (Fig. 69).

Fig. 68. Development of ovarian follicles. Ovulation and Formation of the corpus luteum:

1 — primary (growing) follicles; 2 — mature (vesicular) follicles (Graafian follicles); 3 — ovulation; 4 — corpus luteum; 5 — atretic body; 6 — corpus albicans (scar of corpus luteum); 7 — blood vessels

Fig. 69. Pathway of the oocyte through the uterine tube and embryo implantation into the myometrium (after A. Ham and D. Cormack, 1982):

1 — follicle maturation in the ovary; 2 — ovulation; 3 — sperm penetration into the oocyte; 4 — uterine tube; 5 — formation of the zygote; 6 — Cleavage of the zygote; 7 — entry of the embryo from the lumen of the uterine tube into the uterine cavity; 8 — embryo implantation into the endometrium

Appendages of the ovary. Rudimentary structures—the uterine adnexa (appendages)—are located near each ovary, representing remnants of the tubules of the pronephros/mesonephros (primary/embryonic kidney) and its duct.

The epoophoron (parovarium) is situated between the folds of the peritoneum, superior and lateral to the ovary. It consists of several longitudinal and transverse short tubules.

The paroophoron, comprising several short, narrow tubules, is located near the tubal extremity of the ovary.

Vesicular Appendices (pedunculated hydatids), appearing as small fluid-filled cysts, are located lateral to the ovary, slightly inferior to the funnel of the uterine tube.

The uterus is a single, hollow, thick-walled, pear-shaped organ in whose cavity the embryo (fetus) develops and grows. It is located in the lesser pelvis between the urinary bladder anteriorly and the rectum posteriorly. The uterus consists of a fundus, body, and cervix. The expanded fundus is directed superiorly, with the uterine tubes extending from it laterally. Below the fundus lies the flattened body, and further inferiorly is the narrower and more elongated cervix. The lower (vaginal) part of the cervix is embraced by the upper part of the vagina, into which the external os opens. The body of the uterus is tilted forward relative to its cervix (anteflexion), creating an obtuse angle between the cervix and the body that opens anteriorly. The entire uterus is tilted forward (anteverversion). At the same time, THE POSITION OF the uterus within the lesser pelvis depends on the filling of adjacent organs—the urinary bladder and the rectum.

The narrow, triangular-shaped uterine cavity receives the openings of the uterine tubes at its upper lateral corners. Inferiorly, the uterine cavity communicates with the vagina via the cervical canal. In nulliparous women, the external os is round; in parous women, it appears as a transverse slit.

The uterine wall comprises three layers: the mucosa (endometrium), muscular layer (myometrium), and serosa (perimetrium). The mucous membrane (endometrium) is lined with a single-layered columnar epithelium. Its lamina propria contains numerous tubular uterine glands that penetrate the entire thickness of the mucosa. The mucosa is divided into two layers: a thick superficial functional layer and a deep basal layer. The functional layer is shed during menstruation, whereas the basal layer serves as the source for the regeneration of the functional layer following its shedding. The uterus lacks a submucosa, meaning the mucous membrane is firmly fused with the underlying muscular layer.

The muscular coat of the uterus (myometrium) consists of three layers: internal and external oblique-longitudinal layers, and a middle obliquely oriented circular layer. The fibers of the longitudinal and circular layers interlace with one another. During pregnancy, the smooth Muscle Cells of the myometrium undergo hypertrophy, increasing 5–10 times in length and 3–4 times in thickness. Consequently, by the end of pregnancy, the mass of the uterus reaches 1 kg. Following childbirth, the uterus undergoes gradual involution, returning to its normal size within 6–8 weeks.

The outer coat of the uterus (perimetrium) is formed by the serous membrane, or peritoneum, which covers the uterus superiorly, anteriorly, and posteriorly. The anterior and posterior peritoneal folds converge laterally to form the right and third broad ligaments of the uterus, consisting of two layers. Upon reaching the pelvic walls, these serous folds become continuous with the parietal peritoneum. Situated between the anterior and posterior layers of the broad ligament is the round ligament of the uterus, which is 3–5 mm thick. This ligament originates on the lateral surface of the uterus just inferior to the opening of the uterine tube, then courses laterally and inferiorly, passes through the Inguinal Canal, and extends to the pubic region, where its fibers blend into the subcutaneous adipose tissue.

The uterine (fallopian) tube is a paired, cylindrical organ extending laterally to the right and left from the body of the uterus within the upper part of the broad ligament. In a sexually mature woman, the uterine tube is 8–18 cm long with a lumen width of 2–4 mm. The tube comprises four parts: the uterine (intramural) part, which passes through the uterine wall and opens into its cavity; the short isthmus, located close to the uterus; the long, expanded ampulla; and the infundibulum, which opens via a wide ostium into the peritoneal cavity near the ovary. This opening is fringed by fimbriae, one of which is longer and known as the ovarian fimbria. The mucosa of the uterine tube forms numerous delicate folds.

The vagina is a flattened anteroposteriorly fibromuscular tube 7–9 cm in length that connects the uterine cavity with the female external genitalia. The external orifice of the vagina opens into the vestibule. In virgins, it is partially closed by the hymen. The vaginal mucosa is lined with non-keratinized stratified squamous epithelium and lacks glands. The cells of the superficial epithelial layer are rich in Glycogen, which breaks down through enzymatic processes to form lactic acid. This gives the vaginal secretions an acidic antimicrobial (bactericidal) reaction. External to the mucous membrane lie the muscular coat and the surrounding adventitia. The superior walls of the vagina embrace the cervix, forming a narrow, slit-like vaginal fornix around it, the posterior part of which is deeper.