The Uterine Tubes

The uterine tube, also called the oviduct or fallopian3

tube, is a canal about 10 cm long from the ovary to the uterus. At the distal (ovarian) end, it flares into a trumpet-shaped infundibulum4 with feathery projections called fimbriae5 (FIM-bree-ee); the middle part of the tube is the ampulla; and near the uterus it forms a narrower isthmus. The uterine tube is enclosed in the mesosalpinx6 (MEZ-oh-SAL-pinks), which is the superior margin of the broad ligament.

3Gabriele Fallopio (1528-62), Italian anatomist and physician

4infundibulum = funnel

5fimbria = fringe

6meso = mesentery + salpin = trumpet

Saladin: Anatomy & Physiology: The Unity of Form and Function, Third Edition

Female Reproductive System 1900

Figure 28.1 The Female Reproductive System.

Anterior

Figure 28.1 The Female Reproductive System.

Ovarian — ligament

Medulla—

Cortex-

Tunica— albuginea

Germinal epithelium

Corpus -albicans

Corpus — luteum

Fimbriae of uterine tube

Primordial Secondary Mature follicle follicles follicle Primary follicles Granulosa

Antrum

Suspensory ligament and blood vessels follicles Granulosa

Antrum

Corpus -albicans

Corpus — luteum

Fimbriae of uterine tube

Theca Folliculi

Figure 28.2 Structure of the Ovary and the Developmental Sequence of the Ovarian Follicles.

-Theca folliculi

Corona radiata

—Ovulated oocyte

Figure 28.2 Structure of the Ovary and the Developmental Sequence of the Ovarian Follicles.

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1052 Part Five Reproduction and Development

Infundibulum Ampulla

Isthmus

Fundus Body

Ovarian

Mesosalpinx Uterine

Infundibulum Ampulla

Isthmus

Fundus Body

Ovarian

Mesosalpinx Uterine

Round Ligament Artery

Ovarian artery Ovarian vein

Suspensory ligament

Broad ligament

Broad ligament

Ovarian artery Ovarian vein

Suspensory ligament

Ovary

Broad ligament

Round ligament

Cardinal ligament

Uterosacral ligament

Vagina

Round ligament

Uterus Fundus Body Cervix

Vagina

Cardinal Ligament

Figure 28.3 The Female Reproductive Tract and Supportive Ligaments. (a) Drawing of the reproductive tract, dorsal view. (b) Relationship of the ligaments to the uterine tube and ovary. (c) Photograph of the reproductive tract and supportive ligaments.

Suspensory ligament Uterine tube Fimbriae Infundibulum Ampulla

Ovary

Ovarian ligament

Round ligament

Uterus Fundus Body Cervix

Vagina

Figure 28.3 The Female Reproductive Tract and Supportive Ligaments. (a) Drawing of the reproductive tract, dorsal view. (b) Relationship of the ligaments to the uterine tube and ovary. (c) Photograph of the reproductive tract and supportive ligaments.

The wall of the uterine tube is well endowed with smooth muscle. Its mucosa is extremely folded and convoluted and has an epithelium of ciliated cells and a smaller number of secretory cells (fig. 28.4). The cilia beat toward the uterus and, with the help of muscular contractions of the tube, convey the egg in that direction.

The Uterus

The uterus7 (see fig. 28.3) is a thick muscular chamber that opens into the roof of the vagina and usually tilts forward

7 uterus = womb

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Uterine Epithelium
Figure 28.4 Epithelial Lining of the Uterine Tube. Secretory cells are shown in red and green, and cilia of the ciliated cells in yellow. (Colorized SEM)

over the urinary bladder. Its function is to harbor the fetus, provide a source of nutrition, and expel the fetus at the end of its development. It is somewhat pear-shaped, with a broad superior curvature called the fundus, a midportion called the body (corpus), and a cylindrical inferior end called the cervix. The uterus measures about 7 cm from cervix to fundus, 4 cm wide at its broadest point, and 2.5 cm thick, but it is somewhat larger in women who have been pregnant.

The lumen of the uterus is roughly triangular, with its two upper corners opening into the uterine tubes. It communicates with the vagina by way of a narrow passage through the cervix called the cervical canal. The superior opening of this canal into the body of the uterus is the internal os8 (oss) and its opening into the vagina is the external os. The canal contains cervical glands that secrete mucus, thought to prevent the spread of microorganisms from the vagina into the uterus. Near the time of ovulation, the mucus becomes thinner than usual and allows easier passage for sperm.

Chapter 28 The Female Reproductive System 1053

Insight 28.1 Clinical Application

Pap Smears and Cervical Cancer

Cervical cancer is common among women from ages 30 to 50, especially those who smoke, who began sexual activity at an early age, and who have histories of frequent sexually transmitted diseases or cervical inflammation. It begins in the epithelial cells of the lower cervix, develops slowly, and remains a local, easily removed lesion for several years. If the cancerous cells spread to the subepithelial connective tissue, however, the cancer is said to be invasive and is much more dangerous, potentially requiring hysterectomy9 (removal of the uterus).

The best protection against cervical cancer is early detection by means of a Pap10 smear—a procedure in which loose cells are scraped from the cervix and vagina and microscopically examined. Figure 28.5 shows normal and cancerous Pap smears. The findings are rated on a five-point scale:

Class I-no abnormal cells seen

Class Il-atypical cells suggestive of inflammation, infection, or irritation

Class III-nonmalignant but mildly abnormal cell growth (dysplasia) Class IV-cells typical of localized cancer Class V-cells typical of invasive cancer

An average woman is typically advised to have annual Pap smears for 3 years and may then have them less often at the discretion of her physician. Women with any of the risk factors listed may be advised to have more frequent examinations.

9hyster = uterus + ectomy = cutting out

10George N. Papanicolaou (1883-1962), Greek-American physician and cytologist

Uterine Wall The uterine wall consists of an external serosa called the perimetrium, a middle muscular layer called the myometrium, and an inner mucosa called the endometrium. The myometrium11 constitutes most of the wall; it is about 1.25 cm thick in the nonpregnant uterus. It is composed of bundles of smooth muscle running in all directions, but it is less muscular and more fibrous near the cervix; the cervix itself is almost entirely collagenous. The smooth muscle cells of the myometrium are about 40 ^m long immediately after menstruation, but they are twice this long at the middle of the menstrual cycle and 10 times as long in pregnancy. The function of the myometrium is to produce the labor contractions that help to expel the fetus.

The endometrium12 is the mucosa. It has a simple columnar epithelium, compound tubular glands, and a stroma populated by leukocytes, macrophages, and other cells (fig. 28.6). The superficial half to two-thirds of it,

12endo = inside + metr = uterus

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1054 Part Five Reproduction and Development

1054 Part Five Reproduction and Development

New Epithelium Stumps Basalis Uterus
(a)
Norm Basalis

Figure 28.5 Pap smears. (a) A normal, healthy Pap smear. (b) Pap smear from a patient with class V cervical cancer. How does the ratio of nuclear to cytoplasmic volume change in malignant cervical cells?

Figure 28.5 Pap smears. (a) A normal, healthy Pap smear. (b) Pap smear from a patient with class V cervical cancer. How does the ratio of nuclear to cytoplasmic volume change in malignant cervical cells?

called the stratum functionalis, is shed in each menstrual period. The deeper layer, called the stratum basalis, stays behind and regenerates a new functionalis in the next cycle. When pregnancy occurs, the endometrium is the site of attachment of the embryo and forms the maternal part of the placenta from which the fetus is nourished.

Histological The Endometrium
Figure 28.6 Histology of the Endometrium.

Blood Supply The uterine blood supply is particularly important to the menstrual cycle and pregnancy. A uterine artery arises from each internal iliac artery and travels through the broad ligament to the uterus (fig. 28.7). It gives off several branches that penetrate into the myometrium and lead to arcuate arteries. Each arcuate artery travels in a circle around the uterus and anastomoses with the arcuate artery on the other side. Along its course, it gives rise to smaller arteries that penetrate the rest of the way through the myometrium, into the endometrium, and produce the spiral arteries. The spiral arteries wind tortuously between the endometrial glands toward the surface of the mucosa. They rhythmically constrict and dilate, making the mucosa alternately blanch and flush with blood.

Ligaments The uterus is supported by the muscular floor of the pelvic outlet and folds of peritoneum that form supportive ligaments around the organ, as they do for the ovary and uterine tube (see fig. 28.3a). The broad ligament has two parts: the mesosalpinx mentioned earlier and the mesometrium on each side of the uterus. The cervix and superior part of the vagina are supported by cardinal (lateral cervical) ligaments extending to the pelvic wall. A pair of uterosacral ligaments attach the dorsal side of the

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Chapter 28 The Female Reproductive System 1055

Blood Supply The Female Pelvis
Figure 28.7 Blood Supply to the Female Reproductive Tract.

accompanies the first act of intercourse; however, the hymen is commonly ruptured before then by tampons, medical examinations, or strenuous exercise. The lower end of the vagina also has transverse friction ridges, or vaginal rugae, which stimulate the penis and help induce ejaculation.

The vaginal epithelium is simple cuboidal in childhood, but the estrogens of puberty stimulate it to transform into a stratified squamous epithelium. This is an example of metaplasia, the transformation of one tissue type to another. The epithelial cells are rich in glycogen. Bacteria ferment this to lactic acid, which produces a low vaginal pH (about 3.5-4.0) that inhibits the growth of pathogens. Recall from chapter 27 that this acidity is neutralized by the semen so it does not harm the sperm. The mucosa also has antigen-presenting cells called dendritic cells, which are a route by which HIV from infected semen invades the female body.

uterus to the sacrum, and a pair of round ligaments attach the ventral surface of the uterus to the abdominal wall. The round ligaments continue through the inguinal canals and terminate in the labia majora, much like the guber-naculum of the male terminating in the scrotum.

As the peritoneum folds around the various pelvic organs, it creates several dead-end recesses and pouches. Two major ones are the vesicouterine13 pouch, which forms the space between the uterus and urinary bladder, and rectouterine pouch between the uterus and rectum (see fig. 28.1).

Vagina

The vagina,14 or birth canal, is a tube about 8 to 10 cm long that allows for the discharge of menstrual fluid, receipt of the penis and semen, and birth of a baby. The vaginal wall is thin but very distensible. It consists of an outer adventi-tia, a middle muscularis, and an inner mucosa. The vagina tilts dorsally between the urethra and rectum; the urethra is embedded in its anterior wall. The vagina has no glands, but it is lubricated by the transudation ("vaginal sweating") of serous fluid through its walls and by mucus from the cervical glands above it. The vagina extends slightly beyond the cervix and forms blind-ended spaces called fornices15 (FOR-nih-sees; singular, fornix) (see figs. 28.1 and 28.3a).

At its lower end, the vaginal mucosa folds inward and forms a membrane, the hymen, which stretches across the orifice. The hymen has one or more openings to allow menstrual fluid to pass through, but it usually must be ruptured to allow for intercourse. A little bleeding often

_Think About It_

Why do you think the vaginal epithelium changes type at puberty? Of all types of epithelium it might become, why stratified squamous?

The Vulva (Pudendum)

The external genitalia of the female are collectively called the vulva16 (pudendum17); this includes the mons pubis, labia majora and minora, clitoris, vaginal orifice, and accessory glands and erectile tissues. It occupies most of the perineum (fig. 28.8a).

The mons18 pubis consists mainly of a mound of adipose tissue overlying the pubic symphysis. The labia majora19 (singular, labium majus) are a pair of thick folds of skin and adipose tissue inferior to the mons; the slit between them is the pudendal cleft. Pubic hair grows on the mons pubis and lateral surfaces of the labia majora at puberty, but the medial surfaces of the labia remain hair less. Medial to the labia majora are the much thinner, entirely hairless labia minora20 (singular, labium minus). The area enclosed by them, called the vestibule, contains the urinary and vaginal orifices. At the anterior margin of the vestibule, the labia minora meet and form a hoodlike prepuce over the clitoris.

The clitoris is structured much like a miniature penis but has no urinary role. Its function is entirely sensory, serving as the primary center of erotic stimulation. Unlike the penis, it is almost entirely internal, it has no corpus vesico = bladder 4vagina = sheath 5fornix = arch, vault vulva = covering 7pudend = shameful 8mons = mountain 9labi = lip + major = larger, greater 10minor = smaller, lesser

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1056 Part Five Reproduction and Development

Labium majus Labium minus Vaginal orifice Hymen-

Perineal raphe (a)

Vaginal Himen

Mons pubis

Prepuce

Clitoris

Urethral orifice

Vestibule

Anus

Mons pubis

Prepuce

Clitoris

Urethral orifice

Vestibule

Anus

Perineal raphe (a)

Skene Gland Anatomy
Figure 28.8 The Female Perineum. (a) Surface anatomy; (b) subcutaneous structures. Which of these glands is homologous to the male prostate gland?

spongiosum, and it does not enclose the urethra. Essentially, it is a pair of corpora cavernosa enclosed in connective tissue. Its glans protrudes slightly from the prepuce. The body (corpus) passes internally, inferior to the pubic symphysis (see fig. 28.1). At its internal end, the corpora cavernosa diverge like a Y as a pair of crura, which, like those of the penis, attach the clitoris to each side of the pubic arch. Like the penis, the clitoris is supplied by the internal pudendal arteries, also called the clitoral arteries in the female.

Just deep to the labia majora, a pair of subcutaneous erectile tissues called the vestibular bulbs bracket the vagina like parentheses. They become congested with blood during sexual excitement and cause the vagina to tighten somewhat around the penis, enhancing sexual stimulation.

On each side of the vagina is a pea-sized greater vestibular (Bartholin21) gland with a short duct opening into the vestibule or lower vagina (fig. 28.8b). These glands are homologous to the bulbourethral glands of the male. They keep the vulva moist, and during sexual excitement they provide most of the lubrication for intercourse. The vestibule is also lubricated by a number of lesser vestibular glands. A pair of mucous parau-rethral (Skene22) glands, homologous to the male prostate, open into the vestibule near the external ure-thral orifice.

2,Caspar Bartholin (1655-1738), Danish anatomist

22Alexander J. C. Skene (1838-1900), American gynecologist

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Chapter 28 The Female Reproductive System 1057

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Responses

  • Teresa
    How to stretch penis suspensory lig?
    7 years ago
  • daisy
    How deep is hymen into the vagina?
    7 years ago
  • linda
    Is 28.3 cm normal blood flow to ovary?
    7 years ago
  • cathy
    Where are round ligament?
    7 years ago
  • yemane
    Where Is The Skenes Gland?
    6 years ago
  • Rita
    What are the round ligaments in the pelvic area?
    6 years ago
  • scott graham
    Which one corpus luteum antrum oocyte,primary follicle,corpus albicans,primordial follicle?
    6 years ago
  • tommy salama
    Where are the greater vestibular glands?
    6 years ago
  • luca
    When should you take thyroid medicine?
    6 years ago
  • ruairidh
    What do skenes glands look like?
    6 years ago
  • lewis
    Where is the urethral sponge located?
    6 years ago
  • marcel marquis
    How to express the bartholin gland?
    6 years ago
  • manu
    Where is the hymen located in a female?
    5 years ago
  • fastolph
    What is the function of the female reproductive system?
    5 years ago
  • Darren
    Where are skene glands on a woman?
    5 years ago
  • georgia
    Where is the skene gland located?
    5 years ago
  • rocco angelo
    Where is the female prostate gland?
    3 years ago
  • gebre
    How to stimulate the mons pubis?
    3 years ago
  • Crystal
    What look like vagina after losing himen?
    2 years ago
  • edilio
    How are normal vagina valve looks?
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  • Agnese
    What is the normal vestibule of the vagina?
    2 years ago
  • Jude
    What ligaments house the uterine artery ?
    1 year ago
  • adelard
    Why does the vaginal rugae protrude on urination?
    1 year ago
  • CHRISTOPHER
    What type of tissue comprises the epithelium of the vagina after puberty?
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