THE FEMALE
REPRODUCTIVE ORGAN
Function of the female
reproductive system
1. The
function of the female reproductive system is to produce offspring and thereby
ensure continuity of the genetic code.
2. It
produces eggs or female gametes, which each may unite with a male gamete to
form the first cell of any offspring.
3. It
also can provide nutrition and protection to the offspring for up to several
years after conception.
Structural plan of the female reproductive
system
1. Essential
organs – gonads are the paired ovaries; gametes are ova produced by the ovaries
– the ovaries are also internal genitals.
2. Accessory
organs
a.
Internal
genitals – uterine tubes, uterus and vagina – ducts or duct structures that extend
from the ovaries to the exterior
b.
External genitals – the vulva
The Uterus
1.
Structure of
the uterus
a. Size
and shape of the uterus
(1) The
uterus is pear–shaped and has two main parts – the cervix and the body.
b. The
wall of the uterus is composed of three layers
(1) The
inner endometrium
(2) Middle
myometrium
(3) Outer
incomplete layer of parietal peritoneum
c. Cavities
of the uterus – the cavities are small because of the thickness of the uterine
walls
(1) The
body cavity’s apex constitutes the internal os and opens into the cervical
canal, which is constricted at its lower end and forms the external os that
opens into the vagina.
d. The
blood to the uterus is supplied by uterine arteries
2.
Location of
the uterus
a. The
uterus is located in the pelvic cavity between the urinary bladder and the
rectum.
b. The
position of the uterus is altered by age, pregnancy and distension of related
pelvic viscera
c. The
uterus descends, between birth and puberty, from the lower abdomen to the true
pelvis.
d. The
uterus begins to decrease in size at menopause.
3.
Function of
the uterus
a. The
uterus is part of the reproductive tract and permits sperm to ascend toward the
uterine tubes.
b. If
conception occurs, the offspring develops in the uterus
(1) The
embryo is supplied with nutrients by endometrial glands until production of the
placenta
(2) The
placenta is an organ that permits the exchange of materials between the
mother’s blood and the fetal blood but keeps the two circulations separate.
(3) Myometrial
contractions occur during labor and help push the offspring out of the mother’s
body.
c. If
conception does not occur, outer layers of endometrium are shed during
menstruation
(1) Menstruation
is a cyclical event that allows the endometrium to renew itself.
The Uterine tubes
1. Uterine
tubes are also called Fallopian tubes or oviducts
2. Uterine
tubes are attached to the uterus at its upper outer angles and extend upward
and outward toward the sides of the pelvis
3. Structure
of the uterine tubes
a. Uterine
tubes consist of mucous, smooth muscle and serous lining
b. Mucosal
lining is directly continuous with the peritoneum lining the pelvic cavity
(1) Tubal
mucosa is continuous with that of the vagina and uterus, which means it, may
become infected with organisms introduced into the vagina.
c. Each
uterine tube has three divisions
(1) Isthmus
(2) Ampulla
(3) Infundibulum
4. Function
of the uterine tubes
a. Uterine
tubes serve as transport channels for ova and as the site of fertilization
The Ovaries
1.
Location of
the ovaries
a. The
ovaries are nodular glands located on each of side of the uterus, below and
behind the uterine tubes.
b. Ectopic
pregnancy – development of the fetus in a place other than the uterus.
2.
Microscopic
structure of the ovaries
a. The
surface of the ovaries is covered by the germinal epithelium
b. Ovarian
follicles contain the developing female sex cells.
c. Ovum
– an oocyte released from the ovary
3.
Functions of
the ovaries
a. Ovaries
produce ova – the female gametes
b. Oogenesis
– process that results in formation of a mature egg
c. The
ovaries are endocrine organs that secrete the female sex hormones (estrogens
and progesterone)
The Vagina
1.
The vagina is a tubular
organ located between the rectum, urethra and bladder.
2.
Structure of
the vagina
a. The
vagina is a collapsible tube capable of distension, composed of smooth muscle,
and lined with mucous membrane arranged in rugae.
b. The
anterior wall is shorter than the posterior wall because the cervix protrudes
into its uppermost portion.
c. Hymen
– a mucous membrane that typically forms a border around the vagina in young
pre–menstrual girls.
3.
Functions of
the vagina
a. The
lining of the vagina stimulates the penis during sexual intercourse and acts as
receptacle for semen.
b. The
vagina is the lower portion of the birth canal.
c. The
vagina is a transport for tissue shed during menstruation
The Vulva
1. The
vulva consists of the female external genitals; mons pubis, labia majora, labia
minora, clistoris, urinary meatus, vaginal orifice and greater vestibular
glands.
2. Functions
of the vulva
a. The
mons pubis and labia protects the clitoris and vestibule.
b. Vestibular
glands produce lubrication to reduce friction during intercourse.
c. The
clitoris contains sensory receptors that send information to the sexual
response is of the brain.
d. The
vaginal orifice is the boundary between the internal and external genitals.
The Perineum
1. The
perineum is the skin–covered region between the vaginal orifice and the rectum.
2. This
area may be torn during childbirth
Regulation of secretion of
ovarian hormone
1.
Ovarian cycle – ovaries
from birth contains oocytes in primary follicles in which the meiotic process
has been suspended. At the beginning of menstruation each month, several of the
oocytes resume meiosis. Meiosis will stop again just before the cell is
released during ovulation.
During the
ovarian cycle, the uterus also undergoes cyclic changes (uterine cycle). The
endometrial layer responds to the changes of the ovarian hormones and is the
source of menstrual discharge if pregnancy does not occur. If pregnancy does
occur, the endometrium participates in the formation of placenta.
2.
Endometrial
cycle or menstrual cycle
a. Menses
– a periodic vaginal bleeding, resulting from shielding of the endometrial
lining of the uterus.
b. Post–menstrual
phase
(1) An
early follicle called the primordial follicle is observed in the peripheral
area in the ovarian cortex. It is composed of a primary oocyte that is
surrounded by a single layer of follicular cells. Several primordial follicles
differentiate into primary follicle.
(2) The
layer of follicular cells proliferates and forms a layer of granulosa cells
that surrounds the primary oocyte.
(3) Connective
tissue surrounding the follicle then differentiates to form thecal cells.
(4) The
follicle becomes enlarged because the granulosa cell secrete a fluid that not
only fills spaces between cells but also displaces the oocyte to one side, thus
producing a large cavity in the center of the follicle. This follicle is known
as secondary follicle.
(5) The
follicle further matures to become a Graafian follicle, and although several
follicles begin this process, only follicle reaches the final stage. The rest
degenerates.
(6) The
Graafian follicles produce a bulge in the outer surface of the ovary. The time
required for the development of this mature follicle is approximately 14 days
and this period is known as the follicular phase of the menstrual cycle.
c. Ovulation
– Graafian follicles ruptures and the ovum is expelled from it.
d. Pre–menstrual
phase
The Graafian
follicle remaining in the ovary undergoes change and become known as a corpus
luteum (yellow body). The thecal and granulosa cells undergo changes and
secrete progesterone.
3.
Myometrial
phase
If
fertilization of the ovum does not occur, the corpus luteum ceases to secrete
hormones and becomes non–functional and is known as the corpus albicans (white
body). The time required for this process is about 14 days after ovulation and
is known as the luteal phase of the menstrual cycle.
4.
Gonadotropic
cycle
a. The
hypothalamus releases Gn–RH, which maybe controlled by dopamine (inhibitors)
and norepinephrine (stimulator). The gonadotrope cells of the anterior
pituitary release FSH, which in turn causes the proliferation of the granulosa
cells in the ovary. FSH, therefore, is responsible for the early growth of the
primary follicle. It may also influence the conversion of testosterone to estradiol,
which takes place in the thecal cells. This estradiol that is produced causes
the granulosa cells to form more FSH receptors, making them more sensitive to
FSH. The rising levels of estradiol that occur in the early to mid–follicular
phase inhibit the production of pituitary FSH. However, in the late follicular
phase, rising levels of estradiol cause the pituitary to release LH. This surge
of LH causes ovulation.
b. The
release of Gn–RH from the hypothalamus also causes the anterior pituitary to release
LH. LH acts on the thecal cells of the ovary to induce the synthesis of
androgens and ultimately estradiol. The estrogen produced diffuses into the
granulosa cells. LH is necessary for the final follicular growth and ovulation
and works synergistically with FSH. It influences the change of the granulosa
cells into lutein cells and thus the production of progesterone. It has been
postulated that progesterone may serve in the negative feedback mechanism for
the LH release from the anterior pituitary.
The Cervical mucus
Cervical mucus is a complex secretion
produced by the gland of the endocervix and it has the following
characteristics:
1. It
is composed of 92 – 98% water and approximately 1% inorganic salts, of which
NaCl is the main constituents
2. The
mucus also contains free simple sugars, polysaccharides, proteins and
glycoproteins.
3. Its
pH is usually alkaline and ranges from 6.5 to 9.0
4. Spinnbarkeit
– is the property that allows cervical mucus to be stretched or drawn into a
thread. Spinnbarkeit can be estimated by stretching a sample of mucus between 2
glass slides and measuring the maximum length of the thread before it breaks.
At midcycle, spinnbarkeit usually extends 10cm.
5. Ferning
or arborization refers to the characteristic microscopic pattern cervical mucus
forms when dried on a slide. Ferning results from the crystallization of
inorganic salts around small and optimal amount of organic materials present in
cervical mucus.
The Ovarian hormones
1.
Estrogens are
synthesized by the thecal cells of the ovaries in female and small amounts are
produced by the adrenal cortex in male and female and by the testes in male.
The estrogen metabolites are
a. Estradiol
b. Estrone
c. Estiol
2.
Progesterone is produced
mainly by the granulosa (lutein) cells of the corpus luteum in female. It is
also produced by the placenta in pregnancy, and small amount can be produced by
the adrenal cortex. The main urinary metabolite is pregnanediol.
3.
Dehydroepiandrosterone
(DHEA)
is an androgen primarily derived from the adrenal gland. Its conjugation
product DHEA–sulfate in plasma has replaced the 17–ketosteroid.
4.
Relaxin is
polypeptide that has been extracted from the ovary. In certain animal species,
it appears to play important at the time of parturition, causing relaxation of
the pelvic ligaments and softening of the uterine cervix. It is found in ovary,
blood and placenta. It also increases glycogen synthesis and water uptake by
the myometrium and decreases its contractility.
Laboratory evaluation of
ovarian function
1.
Urine
estrogens
to monitor development of the unborn child during pregnancy.
a. Kober
reaction
involves heating a urine sample in a strong aqueous sulfuric acid solution
containing hydroquinone. After cooling and dilution, the absorbance of the
resulting reddish–brown color is measured and total estrogen concentration
determined.
b. Assay
interferences
(1) Falsely
decreased: ampicillin, neomycin, hydrochlorothiazide
(2) Falsely
elevated: meprobamate, L–dopa, phenolphthalein
2.
Serum
estradiol
to monitor ovarian tumors. Decreased level may be found in primary and
secondary ovarian failure as well as in adrenal gland malfunction.
Reference
range:
a.
Female
Prepubertal 4 – 12 pg/ml
Early
follicular phase 30 – 100 pg/ml
Late
follicular phase 100
– 400 pg/ml
Luteal phase 50 – 150 pg/ml
Post
menopausal 5 – 18 pg/ml
b.
Male
Prepubertal 2 – 8 pg/ml
Adult 10 – 60
pg/ml
3.
Serum
progesterone
has been used primarily for the evaluation of fertility in females, in
particular for the detection of ovulation.
Reference
range:
a. Male 0.12 – 0.3
ng/ml
b. Female
Menstrual
cycle
Follicular phase < 1 ng/ml
Luteal phase 5 – 20 ng/ml
Pregnancy
1st trimester 20 – 50 ng/ml
2nd trimester 50 – 100 ng/ml
3rd trimester 100 – 400 ng/ml
4.
Serum DHEA – S is valuable for
the assessment of adrenal cortical function.
Reference
range:
a. Adult
males 3.6 – 6.3 ng/ml
(12.5 – 21.9 nmol/L)
b. Females
4.4 – 6.0 ng/ml
(15.3 – 20.8 nmol/L)
Inhibitors of ovarian function
1. Gn–RH
– leuprolide, buserelin, nafarelin
2. Tamoxifen
3. Danazol
4. Antiprogestins:
Mifepristone, epostane
5. Antiandrogens:
Cyproterone, cyproterone acetate, ketoconazole
Clinical significance of
Ovarian Function Test
1.
Female
Infertility
a. Uterine
leimyonas, adenomas of smooth muscle cells, are the most common tumors of the
uterus. If present, they can interfere with the implantation of a fertilized
ovum
b. Partial
or total destruction of the endometrial lining of the uterus known as
Asherman’s syndrome, also makes implantation impossible.
c. Tubal
abnormalities usually result in decreased patency of the lumen of the oviducts.
This can be caused by chronic infections as well as endometriosis.
d. Ovarian
abnormalities usually result in anovulation, which is the failure to produce a
mature ovum for fertilization. This condition may be caused by infections,
tumors or polycystic ovary disease (PCOD).
e. At
the pituitary level, hypersecretion of prolactin (PRL) due to an adenoma may
result in infertility. This condition is usually accompanied by amenorrhea and
galactorrhea. Hypersecretion of PRL may also be seen in patients taking certain
medications such as dopamine antagonists or in some cases of hypothyroidism.
f.
If the hypothalamus is not
producing Gn–RH, ovulation will not occur. Tumors of the hypothalamus are rare
causes of disruption of Gn–RH. More common causes include stress, weight loss,
exercise and chronic illness.
2.
Hirsutism
Hirsutism in
women is defined as excessive growth of hair in male distribution. The face,
chest, abdomen and sacral regions are commonly affected. Hirsutism is
associated with normal or moderately increased levels of testosterone.
Virilizaton on
the other hand, is an abnormal development of the secondary male sex
characteristics. These characteristics may include hirsutism but also hoarse
voice, acne, clitoral enlargement and changes in body mass distribution.
Virilization is caused by greatly increased levels of testosterone.
Causes of
hirsutism
a.
Primary
hyperandrogenemia
(1)
Congenital
Adrenal Hyperplasia (CAH) is a genetic disorder characterized
by the deficiency or absence of enzymes involved in the biosynthetic pathway
for the production of cortisol. Since very little cortisol is produced, the
pituitary gland releases ACTH to compensate. The adrenal gland is then
stimulated and produces excessive amounts of the steroid hormones above the
enzymatic block. This usually results in excessive androgen production.
(2)
Polycystic
Ovary Disease (PCOD) linked to an abnormal release of LH by the
pituitary. The hypersecretion of LH causes thecal hyperplasia in the ovary and
thus increased androgen levels.
(3)
Tumors of the
adrenal gland
and ovary can produce massive amounts of androgens.
b.
Secondary
hyperandrogenemia
(1) Pituitary
adenomas, testicular feminization, hypothyroidism and Type II Diabetes mellitus
(2) Excessive
secretion of ACTH, growth hormone and PRL from pituitary
c.
Idiopathic
hirsutism
is a genetically determined increased sensitivity of the hair follicle to
androgens
3.
Amenorrhea
Amenorrhea is the
absence of vaginal bleeding. Amenorrhea can be a physiologic process, such as
occurs with pregnancy, or it can be pathologic. The pathologic causes of
amenorrhea maybe either primary or secondary.
a.
Primary
amenorrhea
is defined as having no previous vaginal bleeding. Among healthy females, 99%
have begun to menstruate by the age of 16. Signs of puberty, such as breast
development and appearance of pubic hair, develop before menarch. If a female
reaches the age of 14 without showing any signs of puberty or having begun to
menstruate, the diagnosis of amenorrhea is made.
Causes of
amenorrhea:
(1) Chromosomal
abnormalities like Turner’s syndrome (gonadal dysgenesis)
(2) Congenital
structural malformation like Mullerian agenesis which is the absence of uterus,
fallopian tubes or vagina.
b.
Secondary
amenorrhea
is defined as the absence of menses for 6 months or for the equivalent three
previous cycle intervals, whichever is longer.
Causes of
secondary amenorrhea:
(1) Weight
loss, strenuous exercise, drugs and stress
(2) Asherman
syndrome
(3) Primary
hypothyroidism
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