Download Dr.Amina Zakaria Al-tutunji M.B.Ch.B., MD. Obstetrics and

Dr.Amina Zakaria Al-tutunji
M.B.Ch.B., MD.
Obstetrics and Gynecology
College of medicine/ University of Mosul
EMBRYOLOGY AND ANATOMY OF FEMALE GENITAL TRACT
EMBRYOLOGY
Development of the genital organs
Following fertilization, the normal embryo contains 23 sets of chromosomes, including 22 autosomes andone sex
chromosomes from each parent.
46xy embryo will develop as a male
46xx embryo will develop as a female.
Its the presence or absence of the y chromosome which determines whether the undifferentiated gonad becomes a
testis or an ovary. Although genetic sex is determined at fertilization, gender is not apparent untill approximatly the
12th week of embryonic life. By the 5th week of embryonic life, both male and female embryos start to develop the
following structures on either side of the midline. as in fig.1
1-genital ridge (proliferation of coelomic epithelium) .
2-mesonephric (wolffian) duct (lateral to the genital ridge).
3-para meso-nephric (Mullerian) duct.
Fig.1 Cross-sectional diagram of the posterior abdominal wall showing the genital ridge
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Development of the uterus and Fallopian tubes
The lower end of the Mullerian ducts come together in the mid line, fuse and develop into the uterus & cervix.
At first there is a septum separating the lumina of the 2 ducts, but later this disappears and a single cavity is formed,
i. e. the uterus. The upper parts of both ducts form the Fallopian tube .The lower end of the fused Mullerian ducts
beyond the uterin luman remains solid forms a cord. As in fig.2
Development of the vagina
The Mullerian ducts reach down to the urogenital sinus and at the meeting point, form the Mullerian tubercle which
meet apair of endodermal sino-vaginal bulb.These sino-vaginal bulbs proliferate and form a solid vaginal plate. By
the 5th month, the vaginal plate is entirely canalized to form vagina.
The luman of vagina remains separated from the urogenital sinus by a thin tissue plate, the hymen. fig.3
Fig.2 development of uterus &fallopian tubes .
Fig.3 development of the vagina
Development of the ovary
If no y chromosome, the gonads, forms an ovary and the oogonia begin to develop within follicles. The primitiv
gonad is first evident in embryos at 5 weeks. It forms as a bulb on the medial aspect of the meso-nephric ridge and
is of triple origin. See fig.4.
*Soelomic epithelium of the genital ridge
*The underlying mesmesoderm
*The primitive germ cells.
The next stage involves the primitive germ cells (now known as oocytes) becoming surrounded by a ring of
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pregranulosa cells, stromal cells. Mitotic division,by which the germ cells have been increasing in numbers, then
csases and they enter the 1st stage of meiosis & prophase arrest. Approximately 7million germ cells are present at 5
months, but at birth this has fallen to 2 million. At the same time, as the ovary descends into the abdominal cavity,
two ligaments develop to help control its descend.
Fig.4 Development of ovary
Development of external genitalia
The female development is a simple progression from
these structures ;
*genital tubercle_______clitoris
*genital folds_______labia minora
*genital swellings________labia majora.
ANATOMY
EXTERNAL GENITALIA
The female external genitalia (the vulva) include
1-The mons pubis
2- The labia majora
3- The labia minora
4- The clitoris
5- The vestibule and the vestibular orifice
6- The greater vestibular glands
.
Fig.5 The vulva
1- The mons pubis
Is composed of fibrofatty tissue, which covers the body of pubic bones. Inferiorly it divides to become
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continuous with the labium majus.
2- The labia majora
Are two folds of skin with underlying adipose tissue bounding either side of the vaginal opening. They
contain sebaceous and sweat glands and a few specialized apocrine glands
3- The labia minora
Are two thin folds of skin that lie between the labia majora. Anteriorly they devide into two to form the
prepuce & frenulum of the clitoris. Posteriorly they fuse to form a fold of skin called fourchette. They
contain sebaceous glands but have no adipose tissue.
4- The clitoris.
Is a small 1cm erectile structure , it covered by ischiocavernosus muscle and it had highly developed
nerve supply.
5- The vestibule
Is the cleft between the labia minora. The urethra, the ducts of the Bartholin's glands & the vagina open in
the vestibule. The vestibular bulbs are two masses of erectile tissue that lie on either side of the vaginal
entrance. They contain rich plexus of veins.
Bartholin's glands, each about the size of a small pea, lie at the base of each bulb & open via a 2 cm duct .
into the vestibule between the hymen & the labia minora. Some times the ducts of this gland obstruct
leading to Bartholin cyst & if infection develop it may lead to Bartholin abscess.
The vaginal orifice is surrounded by the hymen which is a thin fold of mucous membrane across the
entrance to the vagina.There are usually openings in it to allow menses to escape.
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The perineal body
Is a perineal mass of muscular tissue that lies between the anal canal & the lower third of the vagina. Its
apex is at the lower end of the rectovaginal septum & its base is covered with skin & extends from the
fourchette to the anus.
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The urethral orifice
Is immediately anterior to the vaginal orifice, about 2- 3 cm beneath the clitoris. It is about 4 cm in length.
INTERNAL REPRODUCTIVE ORGANS
1-The vagina
2-The uterus
3-The fallopian tubes
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4-The ovaries
See fig.6
Fig.6 Internal female reproductive organs
1-The vagina
It is a fibromuscular canal lined
with stratified squamous epithelium
that leads from the uterus to the vulva.
It is longer in the posterior wall
( around 9 cm) than anteriorly
(approximately 7 cm). The vault of the vagina is divided into 4 fornices ; posterior, anterior & two lateral.
The vaginal walls are rugose with transverse folds allowing it to distend during the process of labour.The
vagina is kept moist by secretions from the the uterine and cervical glands & by some transudation from
its epithelial lining. It has no glands. The epithelium is thick and rich in glycogen, the growth of
Doderlein's bacillus a normal commensal of the vagina that breaks down the glycogen to form lactic acid,
producing a PH of around 4.5.This has a protective role for the vagina against pathogens.
Age changes
#At birth, the vagina is under the influence of maternal oestrogens, so the epithelium iswell developed.
After a couple of weeks, the effects of oestrogen disappear and the PH rises to 7 and the epithelium
atrophies.
# At puberty, the reverse occurs.
# At the menopause,the vagina tends to shrink and the epithelium atrophies.
2- Uterus
It is a fibromuscular organ shaped like an inverted pear, tapering inferiorly to the cervix, and in
non-pregnant state is situated entierly within the pelvis. Its hollow organ and has thick muscular walls.
Pre-pregnancy; 7*5*3 cm; weight 70 g.
Full term; 30*25*20 cmcm; weight 1000 g.
It consist of ....the corpus (body) & the cervix
The corpus
It’s the upper part of the uterus consist of
1-the fundus, the upermost part.
2-cornu, which is the site of insertion of the Fallopian tube.
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3-the isthmus, when uterus tapers to a small central constricted area, ends by attaching to the cervix.
The constriction at the isthmus where the corpus joins the cervix is the anatomical internal os. Uterus is in
anteflexion & anteversion position.
Fig.7 Coronal section of the uterine cavity
The longitudinal axis of the uterus is at right angle to the vagina & normally tilts forwards is called
anteversion & its usually flexed forwards on itself at the isthmus is called anteflexion. As in fig.7 .In
around 20% of women, this tilt is not forwards but backwards-retroversion & retroflexion.
The uterus consists of 3 layers
*peritoneum; the outer serous layer; which covers the body of the uterus anteriorly & posteriorly,
laterally it spreads out to form the leaves of the broad ligament.
*myometrium; the middle muscular layer; forms the main bulk of the uterus .
*endometrium; the inner mucous layer; has tubular glands that dip into the myometrium & covered by a
single layer of columnar epithelium. This epithelium is under go cyclical changes & lost due to effects of
pregnancy & menstruation.
Increase the size during pregnancy is mostly due to hypertrophy of existing cells rather than increase in
number.
Uterus is supported by ligaments (fig.8)
1-transverse cervical (cardinal ligaments)
2-round ligament
3-uterosacral ligaments.
Fig.8 The ligamentous supports of the uterus
(a) Frontal view. (b) Lateral view. 1-transverse cervical lig.; 2-round lig.; 3-uterosacral lig.
The cervix
Is a narrower than the body of the uterus approximately
2.5-3 cm in length. It consist of two parts :
* supra vaginal part :lies in continuation with isthmus,
lined with columner ep.
*vaginal part :protruding into the vagina, lined with
stratified sequamous epithelium.
The squamocolumner junction is also known as the
transformation zone, which is an area of rapid cell division,
therefore, It is the common site of cervical carcinoma
(90%). The begining & the end of the endocervical canal
are called the anatomical internal & external os
respectively.
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Age changes of uterus
* After birth, the disappearance of maternal oestrogens causes the uterus to decrease in length by around
one third & cervix is then twice the length of the uterus.
*At puberty, the corpus grows much faster and the size ratio reverses.
*After menopause, the uterus atrophied, the mucosa becomes very thin, the glands almost disappear &
the wall becomes less muscular.
3-The Fallopian tubes (oviducts)
Each tubeis about 10 cm long & extended outwards from the uterine cornu to end near the ovary. The
tubes convey the ovum from the ovary towards the uterus & its the site of fertilization which provides
oxygenation & nutrition for sperm, ovum and zygote.
It is distiguished in to 4 parts;
1-interstitial part
2-the isthmus
3-ampulla
4-infundibulum
The Fallopian tube run in the upper margin of the broad ligament, part of which, known as
mesosalpinx.The epithelium of the tubes contains two functioning cell types, the ciliated cells & the
secretory cells.
4-The ovaries
In the young adult, they are almond shaped, solid, a greyish pink & approximately 3 cm long, 1.5 cm
wide & 1 cm thick 10g weights. It has a twin functions both steroid production & gametogenesis. It has a
central vascular medulla & an outer thick cortex.
The ovary is the only intra-abdominal structure not to be covered by peritonum.
The ligaments of the ovaries ;1-the ovarian ligaments
2-the suspensory ligaments
3-the
mesovarian carry the blood supply to the ovary.
Age changes
*In the child, they are small structures, 1.5 cm long. They have a smooth surface & at birth contain
between 1 & 2 million primordial follicles.
*At puberty, the ovaries increase in size as a result of proliferation of the stromal cells.
*After the menopause, no active follicles are present & the ovary becomes a small, shrunken with a
wrinkled surface.
The blood supply
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1-Ovarian A.: the cheif source of the blood for ovaries .
2-Uterine A.: corpus branch, cervical-vaginal branch.
3-Vaginal A.: main source of blood for the middle part of vagina.
4-Internal pudendal A.: supply superficial perineum, labia majora, labia minora, lower part of the vagina
& clitoris. See fig.9
The lymphatic drainage
***Vulva, lower⅓ of vagina.___superficial inguinal & femoral LN
***Uterus, cervix and upper⅔ of vagina____internal iliac, obturator & external iliac LN, common iliac
& para aortic LN.
***Ovaries and tubes_______para aortic LN. See fig.10
Fig.9
blood
supply
Fig.10
lympha
tic
drainag
e
The nerve supply of pelvis
Nerve supply of vulva and perineum.
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*Pudendal nerve (S2,3,4) divide into perineal n. supply the vulva.The dorsal n. of the clitoris.
Sensory fibres from the mons and labia also pass in the ilioinguinal and genitofemoral n. to the 1st lumber
root.
*Posteriofemoral cutaneous n. carries sensation from perineum to the S1, 2, 3.
Nerve supply of the pelvic viscera
*Sympathetic n.fibers of the pre aortic plexus are continuous with those of the superior hypogastric
plexus. Below, the superior hypogastric plexus divides, and on each side its fibres are continuous with
fibres passing beside the rectum to join the utero vaginal plexus.
*Para sympathetic fibers from S2, S3, S4 join the utero vaginal plexus. Fibres from (or to) the bladder,
uterus, vagina & rectum join the plexus.
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