The internal genital organs in female include vagina, uterus, fallopian tubes, and the ovaries. These organs are placed internally and require special instruments for inspection.
VAGINA
The vagina is a fibromusculomembranous sheath communicating the uterine cavity with the exterior at the vulva. It constitutes the excretory channel for the uterine secretion and menstrual blood. It is the organ of copulation and forms the birth canal of parturition. The canal is directed upwards and backwards forming an angle of 45° with the horizontal in erect posture. The long axis of the vagina almost lies parallel to the plane of the pelvic inlet and at right angle to that of the uterus. The diameter of the canal is about 2.5 cm, being the widest in the upper part and the narrowest at its introitus. It has got enough power of distensibility as evident during childbirth.
Walls
Vagina has got an anterior, a posterior, and two lateral walls. The anterior and posterior walls are apposed together but the lateral walls are comparatively stiffer especially at its middle, as such it looks ‘H’ shaped on transverse section. The length of the anterior wall is about 7 cm and that of the posterior wall is about 9 cm. The upper end of vagina is above the pelvic floor.
Fornices
The fornices are the clefts formed at the top of vagina (vault) due to the projection of the uterine cervix through the anterior vaginal wall, where it is blended inseparably with its wall. There are four fornices—one anterior, one posterior, and two lateral; the posterior one being deeper and the anterior, most shallow one.
Relations
Anterior
The upper one-third is related with base of the bladder and the lower two-thirds are with the urethra, the lower half of which is firmly embedded with its wall.
Posterior
The upper one-third is related with the pouch of Douglas, the middle-third with the anterior rectal wall separated by rectovaginal septum, and the lower-third is separated from the anal canal by the perineal body.
Lateral
The upper one-third is related with the pelvic cellular tissue at the base of broad ligament in which the ureter and the uterine artery lie approximately 2 cm from the lateral fornices. The middle-third is blended with the levator ani and the lower-third is related with the bulbocavernosus muscles, vestibular bulbs, and Bartholin’s glands.
Structures
Layers from within outwards are:
(a) Mucous coat which is lined by stratified squamous epithelium without any secreting glands;
(b) Submucous layer of loose areolar vascular tissues;
(c) Muscular layer consisting of indistinct inner circular and outer longitudinal and;
(d) Fibrous coat derived from the endopelvic fascia which is tough and highly vascular
Epithelium
The vaginal epithelium is under the action of sex hormones. At birth and up to 10–14 days, the epithelium is stratified squamous under the influence of maternal estrogen circulating in the newborn. Thereafter, up to prepuberty and in postmenopause, the epithelium becomes thin, consisting of few layers only. From puberty till menopause, the vaginal epithelium is stratified squamous and devoid of any gland. Three distinct layers are defined—basal cells, intermediate cells, and superficial cornified cells. The intermediate and superficial cells contain glycogen under the influence of estrogen. These cells become continuous with those covering the vaginal portion of the cervix and extend up to the squamocolumnar junction at the external os. The superficial cells exfoliate constantly and more so in inflammatory or neoplastic condition. Replacement of the superficial cells occurs from the basal cells. When the epithelium is exposed to the dry external atmosphere, keratinization occurs. Unlike skin, it does not contain hair follicle, sweat, and sebaceous gland.
Secretion
The vaginal secretion is very small in amount, sufficient to make the surface moist. Normally, it may be little excess in mid-menstrual or just prior to menstruation, during pregnancy, and during sexual excitement. The secretion is mainly derived from the glands of the cervix, uterus, transudation of the vaginal epithelium, and Bartholin’s glands (during sexual excitement). The pH is acidic and varies during different phases of life and menstrual cycle. Conversion of glycogen in the exfoliated squamous cells to lactic acid by the Doderlein’s bacilli is dependent on estrogen. As such, the pH is more towards acidic during childbearing period and ranges between 4 and 5.5 with average of 4.5. The pH is highest in upper vagina because of contaminated cervical secretion (alkaline). The vaginal secretion consists of tissue fluid, epithelial debris, some leukocytes (never contains more than an occasional pus cell), electrolytes, proteins, and lactic acid (in a concentration of 0.75%). Apart from Doderlein’s bacilli, it contains many pathogenic organism including Clostridium welchii. The glycogen content is highest in the vaginal fornix to the extent of 2.5–3 mg% and is lowest in the lower-third being 0.6–0.9 mg%. Doderlein’s bacillus: It is a rod-shaped gram-positive bacillus which grows anaerobically on acid media. It appears in the vagina 3–4 days after birth and disappears after 10–14 days. It appears again at puberty and disappears after menopause. It probably comes from the intestine. Its presence is dependent on estrogen, and its function is to convert the glycogen present in the vaginal mucosa into lactic acid so that the vaginal pH is maintained towards acidic side. This acidic pH prevents growth of the other pathogenic organisms.
Blood supply
The arteries involved are:
(a) Cervicovaginal branch of the uterine artery;
(b) Vaginal artery—a branch of anterior division of internal iliac or in common origin with the uterine;
(c) Middle rectal;
(d) Internal pudendal.
These anastomose with one another and form two azygos arteries—anterior and posterior.
Veins drain into internal iliac and internal pudendal veins.
Nerve supply
The vagina is supplied by sympathetic and parasympathetic nerves from the pelvic plexus. The lower part is supplied by the pudendal nerve.
Uterus
The uterus is a hollow pyriform muscular organ situated in the pelvis between the bladder in front and the rectum behind
Position
Its normal position is one of the anteversion and anteflexion. The uterus usually inclines to the right (dextrorotation) so that the cervix is directed to the left (levorotation) and comes in close relation with the left ureter.
Measurements of parts
The uterus measures about 8 cm long, 5 cm wide at the fundus and its walls are about 1.25 cm thick. Its weight varies from 50–80 g. It has got the following parts (Fig. 1.9). Body or corpus Isthmus Cervix Body or corpus: The body is further divided into fundus— the part which lies above the openings of the uterine tubes. The body properly is triangular and lies between the openings of the tubes and the isthmus. The superolateral angles of the body of the uterus project outwards from the junction of the fundus and body and are called the cornua of the uterus. The uterine tube, round ligament, and ligament of the ovary are attached to each cornu. Isthmus: The isthmus is a constricted part measuring about 0.5 cm situated between the body and the cervix. It is limited above by the anatomical internal os and below by the histological internal os (Aschoff). Some consider isthmus as a part of the lower portion of the body of the uterus. Cervix: The cervix is the lowermost part of the uterus. It extends from the histological internal os and ends at external os which opens into the vagina after perforating the anterior vaginal wall. It is almost cylindrical in shape and measures about 2.5 cm in length and diameter. It is divided into a supravaginal part—the part lying above the vagina and a vaginal part which lies within the vagina, each measuring 1.25 cm. In nulliparous, the vaginal part of the cervix is conical with the external os looking circular, whereas in parous, it is cylindrical with the external os having bilateral slits. The slit is due to invariable tear of the circular muscles surrounding the external os and gives rise to anterior and posterior lips of the cervix.
Cavity
The cavity of the uterine body is triangular on coronal section with the base above and the apex below. It measures about 3.5 cm. There is no cavity in the fundus. The cervical canal is fusiform and measures about 2.5 cm. Thus, the normal length of the uterine cavity including the cervical canal is usually 6–7 cm
Relations
Anteriorly:
Above the internal os, the body forms the posterior wall of the uterovesical pouch. Below the internal os, it is separated from the base of the bladder by loose areolar tissue
Posteriorly:
It is covered by peritoneum and forms the anterior wall of the pouch of Douglas containing coils of intestine.
Laterally:
The double folds of peritoneum of the broad ligament are attached laterally between which the uterine artery ascends up.
Attachment of the Mackenrodt’s ligament extends from the internal os down to the supravaginal cervix and lateral vaginal wall.
About 1.5 cm away at the level of internal os, a little nearer on the left side is the crossing of the uterine artery and the ureter. The uterine artery crosses from above and in front of the ureter, soon before the ureter enters the ureteric tunnel
Structures
Body
The wall consists of three layers from outside inwards:
1. Perimetrium:
It is the serous coat which invests the entire organ except on the lateral borders. The peritoneum is intimately adherent to the underlying muscles.
2. Myometrium:
It consists of thick bundles of smooth muscle fibers held by connective tissues and are arranged in various directions.
During pregnancy, however, three distinct layers can be identified—outer longitudinal, middle interlacing, and inner circular.
3. Endometrium:
mucous lining of the cavity is called endometrium. As there is no submucous layer, the endometrium is directly apposed to the muscle coat. It consists of lamina propria and surface epithelium. The surface epithelium is a single layer of ciliated columnar epithelium. The lamina propria contains stromal cells, endometrial glands, vessels and nerves. The glands are simple tubular and lined by mucus secreting nonciliated columnar epithelium which penetrate the stroma and sometimes even enter the muscle coat. All the components are changed during menstrual cycles. The endometrium is changed to decidua during pregnancy.
Cervix
The cervix is composed mainly of fibrous connective tissues. The smooth muscle fibers average 10–15%. Only the posterior surface has got peritoneal coat.
Epithelial lining of cervix
Endocervical canal and glands:
There is a median ridge on both the anterior and posterior surface of the canal from which transverse folds radiate. This arrangement is called arbor vitae uteri. The canal is lined by single layer of tall columnar epithelium with basal nuclei. Those placed over the top of the folds are ciliated. There are patches of cubical basal or reserve cells underneath the columnar epithelium. These cells may undergo squamous metaplasia or may replace the superficial cells. The glands which dip into the stroma are of complex racemose type and are lined by secretory columnar epithelium. There is no stroma unlike the corpus and the lining epithelium rests on a thin basement membrane. The change in the epithelium and the glands during menstrual cycle and pregnancy are not so much as those in the endometrium.
Portio vaginalis:
It is covered by stratified squamous epithelium and extends right up to the external os where there is abrupt change to columnar type. The transitional zone (transformation zone) may be of 1–10 mm width with variable histological features. The zone consists of endocervical stroma and glands covered by squamous epithelium. The zone is not static but changes with hormone level of estrogen. The site is constantly irritated not only by hormones but also by infection and trauma. Thus, there is more chance of severe dysplasia, carcinoma in situ or even invasive carcinoma at this zone.
Secretions
The endometrial secretion is scanty and watery. The physical and chemical properties of the cervical secretion change with menstrual cycle and with pregnancy. The cervical glands secrete an alkaline mucus with pH 7.8. The mucus is rich in fructose, glycoprotein, and mucopolysaccharides. It also contains sodium chloride. The fructose has got nutritive function to the spermatozoa. Under estrogenic stimulation, glycoprotein network is arranged parallel to each other thus facilitating sperm ascent. Progesterone produces interlacing bridges thereby preventing sperm penetration. Cervical mucus contributes significantly to the normal vaginal discharge. A part forms the mucus plug which functionally closes the cervical canal and has got bacteriolytic property.
Blood Supply
Arterial supply:
The arterial supply is from the uterine artery—one on each side. The artery arises directly from the anterior division of the internal iliac or in common with superior vesical artery. The other sources are ovarian and vaginal arteries to which the uterine arteries anastomose. The uterine artery crosses the ureter anteriorly about 1.5 cm away at the level of internal os before it ascends up along the lateral border of the uterus in between the leaves of broad ligament. The internal blood supply of the uterus is shown in.
Veins:
The venous channels correspond to the arterial course and drain into internal iliac veins.
Nerve supply
The nerve supply of the uterus is derived principally from the sympathetic system and partly from the parasympathetic system.
Sympathetic components are from T5 and T6 (motor) and T10 to L1 spinal segments (sensory).
The somatic distribution of uterine pain is that area of the abdomen supplied by T10 to L1.
The parasympathetic system is represented on either side by the pelvic nerve which consists of both motor and sensory fibers from S2, S3, S4 and ends in the ganglia of Frankenhauser which lies on either sides of the cervix.
The cervix is insensitive to touch, heat and also when it is grasped by any instrument.
The uterus, too is insensitive to handling and even to incision over its wall.
Changes of uterus with Age
At birth, the uterus lies in the false pelvis; the cervix is much longer than the body. In childhood, the proportion is maintained but reduced to 2:1.
At puberty, the body is growing faster under the action of ovarian steroids (estrogens) and the proportion is reversed to 1:2 and following childbirth, it becomes even 1:3.
After menopause the uterus atrophies; the overall length is reduced; the walls become thinner, less muscular but more fibrous.
Position of the uterus
The normal position of the uterus is anteversion and anteflexion.
Anteversion relates the long axis of the cervix to the long axis of vagina which is about 90°.
Anteflexion relates the long axis of the body to the long axis of the cervix and is about 120°.
In about 15–20%, normally the uterus remains in retroverted position.
In erect posture, the internal os lies on the upper border of the symphysis pubis and the external os lies at the level of ischial spines.
FALLOPIAN TUBE (syn: uterine Tube)
The uterine tubes are paired structures, measuring about 10 cm (4") and are situated in the medial three-fourth of the upper free margin of the broad ligaments.
Each tube has got two openings, one communicating with the lateral angle of the uterine cavity, called uterine opening and measures 1 mm in diameter, the other is on the lateral end of the tube, called pelvic opening or abdominal ostium and measures about 2 mm in diameter.
Parts:
There are four parts, from medial to lateral, they are—
(1) Intramural or interstitial lying in the uterine wall and measures 1.25 cm (1/2") in length and 1 mm in diameter;
(2) Isthmus almost straight and measures about 2.5 cm (1") in length and 2.5 mm in diameter;
(3) Ampulla—tortuous part and measures about 5 cm (2") in length which ends in wide
(4) Infundibulum measuring about 1.25 cm (1/2") long with a maximum diameter of 6 mm.
The abdominal ostium is surrounded by a number of radiating fimbriae, one of these is longer than the rest and is attached to the outer pole of the ovary called ovarian fimbria.
Structures—
it consists of three layers:
1. Serous:
Consists of peritoneum on all sides except along the line of attachment of mesosalpinx.
2. Muscular:
Arranged in two layers—outer longitudinal and inner circular.
3. Mucous membrane
Is thrown into longitudinal folds. It is lined by columnar epithelium, partly ciliated, others secretory nonciliated and ‘Peg cells’.
The epithelium rests on delicate vascular reticulum of connective tissue. There is no submucous layer nor any glands.
Changes occur in the tubal epithelium during menstrual cycle but are less pronounced and there is no shedding.
Functions:
The important functions of the tubes are—
(1) Transport of gametes;
(2) To facilitate fertilization;
(3) Survival of zygote through its secretion.
Blood supply:
Arterial supply is from the uterine and ovarian.
Venous drainage is through the pampiniform plexus into the ovarian veins.
Nerve supply:
The nerve supply is derived from the uterine and ovarian nerves. The tube is very much sensitive to handling.
Ovary
The ovaries are paired sex glands or gonads in female which are concerned with:
1. Germ cell maturation, storage and its release
2. Steroidogenesis.
Each gland is oval in shape and pinkish-gray in color and the surface is scarred during reproductive period.
It measures about 3 cm in length, 2 cm in breadth and 1 cm in thickness. Each ovary presents two ends—tubal and uterine, two borders—mesovarium and free posterior and two surfaces—medial and lateral.
The ovaries are intraperitoneal structures. In nulliparae, the ovary lies in the ovarian fossa on the lateral pelvic wall. The ovary is attached to the posterior layer of the broad ligament by the mesovarium, to the lateral pelvic wall by infundibulopelvic ligament and to the uterus by the ovarian ligament.
Relations:
Mesovarium or anterior border—a fold of peritoneum from the posterior leaf of the broad ligament is attached to the anterior border through which the ovarian vessels and nerves enter the hilum of the gland.
Posterior border is free and is related with tubal ampulla. It is separated by the peritoneum from the ureter and the internal iliac artery. Medial surface is related to fimbrial part of the tube. Lateral surface is in contact with the ovarian fossa on the lateral pelvic wall.
The ovarian fossa is related superiorly to the external iliac vein, posteriorly to ureter and internal iliac vessels and laterally to the peritoneum separating the obturator vessels and nerves. structures The ovary is covered by a single layer of cubical cell known as germinal epithelium. It is a misnomer as germ cells are not derived from this layer. The substance of the gland consists of outer cortex and inner medulla.
Cortex:
It consists of stromal cells which are thickened beneath the germinal epithelium to form tunica albuginea. During reproductive period (i.e. from puberty to menopause), the cortex is studded with numerous follicular structures, called the functional units of the ovary in various phases of their development. These are related to sex hormone production and ovulation.
The structures include primordial follicles, maturing follicles, Graafian follicles and corpus luteum. Atresia of the structures results in formation of atretic follicles or corpus albicans.
Medulla:
It consists of loose connective tissues, few unstriped muscles, blood vessels, and nerves. There are small collection of cells called “hilus cells” which are homologous to the interstitial cells of the testes.
Blood supply
Arterial supply
is from the ovarian artery, a branch of the abdominal aorta.
Venous drainage
is through pampiniform plexus, that forms the ovarian veins which drain into inferior vena cava on the right side and left renal vein on the left side. Part of the venous blood from the placental site drains into the ovarian and thus may become the site of thrombophlebitis in puerperium.
Nerve supply
Sympathetic supply comes down along the ovarian artery from T10 segment. Ovaries are sensitive to manual squeezing.
FEMALE URETHRA
The female urethra extends from the neck of the bladder to the external urethral meatus. It measures about 4 cm and has a diameter of about 6 mm.
The bladder base forms an angle with the posterior wall of the urethra called posterior urethrovesical angle (PUV) which normally measures 100°. The urethra runs downwards and forwards in close proximity of the anterior vaginal wall. About 1 cm from the lower end, it pierces the triangular ligament. It ultimately opens into the vestibule about 2.5 cm below the clitoris.
Relations
Posteriorly:
It is related to the anterior
vaginal wall to which it is loosely separated in the upper two-third but firmly adherent in the lower-third.
Anteriorly:
It is related to the posterior aspect of symphysis pubis. The upper two-third is separated by loose areolar tissue; the lower one-third is attached on each side of the pubic rami by fibrous tissue called—pubourethral ligament.
Laterally:
As it passes through the triangular ligament, it is surrounded by compressor urethra. Whether the medial fibers of puborectalis get attached to the urethra while passing by its sides to get attached to lateral vaginal walls is debatable. Bulbocavernosus and vestibular bulb.
Glands:
Numerous tubular glands called paraurethral glands open into the lumen through ducts. Of these, two are longer and called Skene’s ducts which open either on the posterior wall just inside the external meatus or into the vestibule. Skene’s glands are homologous to the prostate in the male.
Sphincters—
the following are the sphincters:
At the urethrovesical junction, there is intricate decussation of the involuntary muscles.
This has the effect of forming anterior and posterior slings which function as an involuntary internal sphincter. This is the lissosphincter.
When the detrusor muscle actively contracts, the slings relax → funneling of the bladder neck → urine flows into the urethra.
The wall of the urethra is composed of involuntary muscles and the fibers are arranged in the form of crossed spirals. The fibers are continuous with those of the bladder detrusor. The tone and elasticity of these muscles keep it close except during micturition. Sphincter urethra in the urogenital diaphragm. This sphincter allows the voluntary arrest of urine flow. Although debatable, puborectalis part of levator ani which surrounds the lower-third of the urethra acts as an external sphincter. Superficial perineal muscles, bulbocavernosus and ischiocavernosus form an accessory external sphincter. Structures: Mucous membrane is lined by transitional epithelium except at the external urethral meatus where it becomes stratified squamous. Submucous coat is vascular. Muscle coat is composed of involuntary muscles and the fibers are arranged in the form of crossed spirals.
Blood supply
Arterial supply:
Proximal part is supplied by the inferior vesical branch and the distal part by a branch of internal pudendal artery. The veins drain into vesical plexus and into internal pudendal veins.
Nerves
The urethra is supplied by the pudendal nerve. development The urethra is developed from the vesicourethral portion of the cloaca.
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