Human Anatomy - M.M. Kurepina, A.P. Ozhigova, A.A. Nikitina 2010

Internal Organs
Reproductive System
Female Reproductive Organs

The Internal female reproductive Organs include the Ovaries, the Uterus with its tubes (oviducts), and the Vagina (Atl. Figs. 210, 211).

The ovaries (ovaria) are paired, ellipsoid-shaped FEMALE REPRODUCTIVE ORGANS. In an adult woman, their length reaches 3—5 cm, and their weight is 5—8 g (Atl. Fig. 211). The size and mass of the ovaries depend on age, functional state, and individual characteristics.

The ovaries are located in the peritoneal cavity on either side of the uterus and lie adjacent to the lateral walls of the lesser pelvis. The Ovary is attached to the broad ligament of the uterus below the fallopian tube by the mesovarium. One end of the ovary faces the uterine wall and is connected to it by the proper ligament of the ovary. The other, more rounded end lies near the fimbriae of the fallopian tube.

Vessels and nerves enter through the hilum of the ovary via the mesovarium. This area is a narrow, slit-like groove.

The surface of the ovary is uneven, which is associated with The Development of Female Germ Cells within it (Fig. 4.52). Scars visible On the surface form after ovulation at the site of a ruptured follicle or a corpus luteum that has atrophied after Pregnancy.

The ovaries are covered by a simple cuboidal epithelium, which flattens with age on prominent surfaces. Directly beneath the epithelium lies the cortex, which contains a well-developed Connective Tissue stroma. In the superficial layers of the cortex, fibers running parallel to the ovarian surface predominate, forming its tunica albuginea (Atl. Fig. 213). Blood Vessels in this layer of the ovary are poorly developed. The rest of the cortex contains A large number of connective tissue cells. In the centrally located medulla, the connective tissue stroma lacks an ordered Organization. It contains numerous elastic fibers, isolated smooth Muscle cells, Lymphatic vessels, spiral Arteries, and well-developed venous plexuses. Individual arteries and Veins branch from the medullary vessels into the cortex. Female germ cells develop within the follicles of the ovarian cortex.

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Fig. 4.52. Surface of the ovary. Arrows indicate ovulating follicles

When the maturation of the cells (oocytes) is complete, the follicular wall ruptures, and ovulation occurs. During this process, the oocyte is released from the ovary, enters the peritoneal cavity, and is captured by the fimbriae of the oviduct.

After ovulation, the follicle collapses, its edges close, and the wall forms numerous folds. A corpus luteum forms at the site of this follicle (Atl. Fig. 214). The follicular cells increase in size and transform into luteal cells capable of synthesizing Steroid Hormones (progesterone). Numerous blood capillaries grow between the cells from the outer layer, and the corpus luteum turns into an endocrine gland. If Fertilization does not occur, the corpus luteum Functions for 10—12 days and then regresses. In the event of pregnancy, it grows up to 5 cm and persists until delivery. During the initial period of pregnancy, its hormones maintain the uterine mucosa, where the embryo has implanted, in a functional state.

The uterine, or fallopian, tubes, also called oviducts (tubae uterinae), are paired and run almost horizontally on both sides of the uterus. Each tube reaches 10—12 cm in length, 5 mm in thickness, and has a lumen diameter of 0.5—2 mm (Atl. Fig. 211). The outer end of the tube opens into the peritoneal cavity through an expanded opening called the infundibulum, the edges of which are fringed to form fimbriae. One of the fimbrial projections is attached to the margin of the ovary. The peritoneal cavity communicates with the external environment through the fallopian tubes, uterus, and vagina. Immediately behind the infundibulum is the expanded portion—the ampulla of the fallopian tube. Near the uterus, it transitions into a short, narrowed part—the isthmus, followed by the uterine part of the tube. Its end has a very small lumen and opens into the uterine cavity. The fallopian tube enters the uterus at the junction between its fundus and body.

Laterally and superiorly, the fallopian tube is covered by a serous membrane—the Peritoneum, while its inferior surface faces the lumen of the broad ligament of the uterus and is devoid of peritoneum. At the transition of the broad ligament from the tube to the ovary, the mesosalpinx (mesentery of the fallopian tube) is formed. Beneath the serosal layer lies connective tissue, which forms the adventitia (outer coat) of the tubal wall. It is covered by the visceral peritoneum.

The middle coat (muscularis) is formed by two layers of Cytology/cytology/32.html">Smooth Muscle tissue: an outer longitudinal layer and an inner circular layer. The inner layer is most pronounced near the uterus. The tone and strength of the muscular layer's contractions are influenced by Ovarian Hormones. The strongest peristaltic contractions occur at the time of ovulation. This increases the mobility of the fimbriae of the infundibulum, which also facilitate the movement of the egg toward the uterus.

The inner layer—the mucosa—forms broad longitudinal folds, which are most pronounced in the ampulla of the tube. The mucosa is lined with a simple ciliated epithelium, which contains numerous secretory cells (Fig. 4.53). The secretion they produce creates favorable conditions for the transport and Nutrition of the egg. The Structure of the epithelial cells varies depending on the phase of the cycle. The cells reach their maximum height (30 µm) by the time of ovulation. Immediately after menstruation, the cells decrease in size.

Thus, the egg, which is incapable of independent movement, moves slowly along the fallopian tube due to the contractions of its muscular coat and the beating of the cilia of the ciliated epithelium. After 9—10 days, the egg reaches the uterine cavity. Fertilization of the egg by a sperm also takes place in the tube. If fertilization does not occur, the egg dies and is shed with the menstrual flow.

Fig. 4.53. Fallopian tube:

A — structure; cross-section: 1 — folds of the mucosa lined with ciliated epithelium; 2 — lamina propria of the mucosa; 3 — muscular coat; 4 — blood vessel; 5 — serosa; B — scanning electron micrograph of the oviduct mucosa: 1 — cilia of ciliated cells; 2 — secretory droplets (after Afanasyev)

The uterus (uterus) is an unpaired hollow muscular organ that serves to gestate the fetus. The uterus is located in the cavity of the lesser pelvis between the Pubic Symphysis and the sacrum (Atl. Fig. 210). The shape of the uterus is pear-shaped, flattened in the anteroposterior direction. The shape and size of the uterus change depending on the functional state of the body (pregnancy, etc.) (Fig. 4.54). In a non-pregnant, nulliparous woman, the uterine cavity is slit-like (Atl. Fig. 211), its capacity does not exceed 3—4 cm³; the muscular wall is thick (2.5 cm); the weight reaches 50 g, and the length is 5 cm. In parous women, these values are 1.5—2 times greater.

The uterus is divided into an upper part—the fundus, a middle part—the body, and a lower part—the cervix. The cervix is the thickest-walled part of the organ; its lower end projects into the vagina and is traversed by a cylindrical canal. At the lower end of the cervix, There is a round (in nulliparous) or oval (in parous) opening through which the uterine cavity communicates with the vagina. The body of the uterus is roughly triangular in shape. Its anterior surface lies adjacent to the Urinary Bladder, and its posterior surface is adjacent to the Small Intestine and rectum. The Fundus of the uterus lies 1—2 cm below the pelvic inlet plane. In the region of the upper-lateral angles of the uterine fundus, the fallopian tubes open into it. When the bladder is empty, the uterus is tilted slightly forward and is even bent forward at the transition between its body and cervix.

Fig. 4.54. Changes in the position and size of the uterus at various stages of pregnancy (numbers indicate the gestational age in weeks)

The fundus, body, and part of the cervix of the uterus are located intraperitoneally. From the uterus, the peritoneum reflects onto adjacent organs, forming recesses or pouches at their boundaries—the vesicouterine and rectouterine pouches. At the transition into the broad ligaments, the peritoneum is connected to the uterus by looser connective tissue layers. The lower half of the anterior surface of the cervix is not covered by peritoneum and is separated from the surface of the urinary bladder by a connective tissue layer.

The uterine wall consists of three layers: the endometrium, myometrium, and perimetrium.

The endometrium, or mucosa, is fused with the muscular layer of the uterine wall. It consists of an epithelium (simple columnar or ciliated) and a lamina propria of connective tissue. The endometrium is penetrated by numerous tubular glands, which in some places reach the myometrium and open onto the epithelial surface. In the cervical region, the glands secrete a thick mucus that plugs its canal. This "mucus plug" protects the uterine cavity from The entry of microflora from the vagina.

The Superficial layer of the endometrium undergoes characteristic changes during the Menstrual cycle and is almost completely shed at its end. If pregnancy occurs, the embryo embeds (implants) into the mucosa, and the Placenta is formed. The deep basal layer remains virtually unchanged during pregnancy and the menstrual cycle, is not shed, and is responsible for the regeneration of the superficial layer (Atl. Fig. 212).

The mucosa of the fundus and body of the uterus does not form folds. In the cervix, there are longitudinal palmate folds. At the site of entry of the fallopian tubes, the endometrium transitions into their mucosa.

The myometrium is a thick muscular layer that forms the bulk of the uterine wall. It consists of several longitudinal, circular, and spiral interwoven layers of smooth muscle cells separated by connective tissue. In addition, some muscle cells are arranged circularly around the spiral arteries. The myometrium has a well-developed vascular network, especially the venous plexus. During pregnancy, intensive growth of smooth muscle tissue occurs. Individual cells can increase nearly 10-fold in length and several-fold in thickness. New cells can also form through the division of numerous pericytes, as well as existing smooth muscle cells. Myometrial growth is hormonally controlled. Due to this intensive growth, the weight of the uterus reaches 2 kg before childbirth, and its cavity increases to 2500 cm³, i.e., 600-fold. However, as early as 1.5 months after delivery, the organ returns to almost its original size.

The perimetrium is formed by a serous membrane covered with mesothelium and connective tissue fused with the myometrium.

Ligaments of the uterus, tubes, and ovaries.

Most of the uterus is covered by peritoneum—the perimetrium—which envelops the organ anteriorly and posteriorly and, converging at its sides, forms the broad ligament of the uterus (Atl. Fig. 211). The latter consists of two layers of peritoneum (anterior and posterior) that extend to the lateral walls of the lesser pelvis. Stretched in the frontal plane within the pelvic cavity, the broad ligament encloses within its layers the fallopian tubes, ovarian ligaments, as well as the blood vessels and nerves supplying the uterus, tubes, and ovaries.

On each side, the round ligament of the uterus runs within the broad ligament (see Atl.). Arising from the anterior surface of the uterus below the tubal ostium, the round ligament courses toward the Inguinal Canal and, passing through it, blends with connective tissue fibers into the subcutaneous tissue. The round ligaments prevent the Displacement of the uterus posteriorly and laterally.

The cervix is anchored posteriorly by the uterosacral ligaments and anteriorly by the vesicouterine ligaments, which allow it to be flexibly attached to the walls of the lesser pelvis and adjacent organs.

The ovaries are anchored by the mesovarium and two ligaments: the ovarian ligament proper and the suspensory ligament. The mesovarium connects the ovary to the posterior layer of the broad ligament of the uterus. The ovarian ligament proper connects the ovary to the uterine body near the tubal insertion. The suspensory ligament is a fold of the parietal peritoneum that extends to the lateral pole of the ovary, carrying blood vessels and nerves. This ligament contains smooth muscle fibers and is therefore capable of changing its length, providing mobile fixation of the ovary.

The vagina is an anteroposteriorly flattened tube connecting the uterus to the external genitalia (Atl. Figs. 210, 211). Superiorly, a significant portion of the cervix projects into the vaginal cavity. The PARTS OF THE vagina surrounding it are called the vaginal fornices. The vagina is located in the middle of the lower pelvis, above the perineal Muscles. The urinary bladder and Urethra lie adjacent to the anterior wall, while the rectum lies adjacent to the posterior wall. The peritoneum reflects from the rectum onto the upper part of the posterior wall. In virgins, the vaginal opening is covered by a fold of mucous membrane, the hymen.

The vaginal mucosa is firmly fused with the muscular layer and is lined with stratified squamous epithelium. This epithelium undergoes hormone-driven changes throughout the cycle. The mucosa forms transverse folds (rugae), which are particularly numerous in the lower part of the vagina. These folds disappear after childbirth. Additionally, there are longitudinal ridges (vaginal columns) on the mucosa of the anterior and posterior surfaces. The mucosa lacks glands, is richly vascularized, and contains lymphatic nodules and numerous elastic fibers that interlace with the muscular layer of the wall. The muscularis forms the middle layer, dominated by longitudinally oriented smooth muscle cells. The adventitia consists of loose connective tissue that connects the vagina to surrounding organs.

Semen is deposited and menstrual flow is discharged through the vagina; it also serves as the birth canal.

External genitalia. The female external genitalia include the pudendal cleft, hymen, Labia Majora, Labia minora, and Clitoris (see Atl.). They represent a complex of structures located around the vaginal opening and together form the vulva. The outermost parts of the vulva—the labia majora—are paired Skin folds rich in adipose tissue. At their base, the ducts of glands open, secreting a white, alkaline fluid that lubricates the pudendal cleft. Within the cleft, between the labia majora, lies a second pair of smaller, highly vascular skin folds devoid of adipose tissue. These are the labia minora. Vascular plexuses are well developed within their connective tissue. At their anterior convergence, and partially covered by them, lies the clitoris—a small, erectile organ homologous to the corpora cavernosa of the male Penis. Approximately midway between the clitoris and the vaginal opening is the external urethral orifice. The vaginal opening is located in the posterior part of the vulva and, in virgins, is partially covered by a thin fold of tissue known as the hymen.

The Mammary Glands (mammae) (breasts) are paired structures located on the surface of the pectoralis major and serratus anterior muscles. Depending on age and functional state, the cellular structure is quite complex, as they produce numerous milk components. Milk consists of Lipids (triglycerides, Fatty acids), Proteins (casein, lactoglobulins, lactalbumins), CARBOHYDRATES (lactose and others), salts, Vitamins, Trace Elements, Lysozyme, IMMUNOGLOBULINS, Water, and several other components. Milk components are secreted into the alveolar lumen as droplets of various sizes. Within the alveolar cavity, these droplets form a fine emulsion and fill the lumen. The ejection of milk into the lactiferous ducts occurs due to the presence of myoepithelial cells at the periphery of the secretory units. Upon contraction, they squeeze milk into the excretory ducts.