Histology of the
Female Genital System
The Female Genital System
The female genital system consists of:
1. Primary sex organ: two ovaries.
2. Accessory sex organs:
1. two oviducts (Fallopian tubes).
2. a uterus.
3. a vagina.
4. external genitalia.
5. two mammary glands.
THE OVARIES
The Ovaries
The ovary is a flattened almond-shaped
small body, divided into peripheral cortex
and central medulla.
The cortex is broad and contains the
ovarian follicles separated by the interfollicular tissue.
The medulla consists of highly vascular
connective tissue, having elastic fibers,
smooth muscle fibers, lymphatics and
nerves.
Stroma of The Ovaries
Tunica albugenia is the covering
connective tissue capsule of the ovary. It
is formed of white collagenous
connective tissue fibers.
Stromal cells: are fusiform cells with oval
nuclei similar to fibroblasts. They are
present between the ovarian follicles.
Reticular connective tissue: present inbetween the ovarian follicles.
Parenchyma of The Ovaries
1. The ovarian follicles. In different stages
of development and degeneration.
2. The endocrine cells: polygonal in shape,
with central rounded nuclei. Their
cytoplasm is rich in lipoid granules. In
animals, they secrete female hormones,
but not in humans.
The germinal epithelium: it covers the
ovary from outside. It is simple cuboidal
in young females and simple squamous
in adults.
The Ovarian Follicles
1.
2.
3.
4.
They are present mainly in the cortex of the
ovary under the tunica albuginea. They are:
Primordial follicles.
Primary follicles.
Secondary follicles.
Mature follicles.
At birth, the average number of 1ry follicles is
4000, only 400 ova are produced during the
reproductive period of the adult female. The
remaining follicles degenerate and change to
atretic follicles which are converted to white
connective tissue bodies.
(1) Primordial Follicles
They are derived from the primordial germ
cells in the yolk sac and then migrate to the
developing ovary.
They are formed of central primary oocytes
which are surrounded by a single layer of
simple squamous cells called follicular
cells.
The oocyte is a large cell with large
eccentric vesicular nucleus with a large
nucleolus. Its cytoplasm contains a welldeveloped Golgi apparatus, RER,
mitochondria and lipid droplets.
(2) Primary Follicle
The oocyte enlarges and develops Golgi
apparatus, ribosomes and mitochondria.
It becomes surrounded by a thick highly
acidophilic glycoprotein coat, called zona
pellucida.
The flat follicular cells becomes cuboidal
and multiply to give rise several layers
(stratified) called granulosa cells.
The connective tissue surrounding the
follicle condenses and forms two layers;
inner highly vascular secretory layer, theca
interna and outer fibrous layer, theca
externa.
(3) Secondary Follicle
The granulosa cells reach 6-12 layers and
start to secrete fluid which forms irregular
spaces between the granulosa cells.
The spaces gradually fuse to form a
crescentic space called antrum which
contains liquor folliculi.
The liquor folliculi contains growth factors,
steroid and gonadotrophic hormones.
The oocyte is eccentric and is surrounded by
a mass of granulosa cells called cumulus
oophorus.
The oocyte starts its first meiotic division
and remains in the prophase until ovulation.
(4) Mature Graafian Follicle
The primordial follicle reaches maturity in
10-14 days and occupies the whole
thickness of the cortex and bulges out on
the free surface of the ovary.
The liquor folliculi accumulates between
the cells of cumulus oophorus freeing the
oocyte from the cells except for one layer
called corona radiata cells.
The granulosa cells secrete estrogen.
The ovum is the largest cell in the body.
It has a large, rounded eccentric nucleus
Ovulation
It occurs between day 10-14 of the ovarian
cycle.
It is under influence of LH of pituitary.
The Graafian follicle rupture through the
stigma due to increase of liquor folliculi.
After ovulation, the oocyte with its
surrounding corona radiata enters the
oviduct, complete its first meiotic division
and start the second meiotic division (which
is completed after fertilization).
The remaining of the mature follicle is
transformed into corpus luteum.
Corpus Luteum
It is considered as a temporary endocrine
organ.
Basement membrane between theca
interna and granulosa cells dissolves, and
capillaries grow in-between granulosa cells.
After ovulation, granulosa cells enlarge and
accumulate lipid droplets and called
granulosa lutein cells.
Under influence of LH, the granulosa cell
secrete progesterone and estrogen.
The same also happens to theca interna
cells which are now called theca lutein cells
Fate of Corpus Luteum
If pregnancy occurs, it enlarges
and continues to function for 3
moths till the placenta is formed
and take the gob.
If pregnancy does not occur, it
degenerates and is transformed
into fibrous tissue called corpus
albicans.
THE OVIDUCT
The Oviduct
It extends from the ovary to the uterus.
It is divided into 4 segments:
1. Infundibulum: funnel-shaped
opening, having finger-like processes
(fimbriae).
2. Ampulla: the widest part, where
fertilization usually occurs.
3. Isthmus: narrow part near to uterus.
4. Intramural part: traverses the uterine
wall
Histology of the Oviduct
1. Mucosa: highly folded and is formed of
A. Epithelium: simple columnar, partly
ciliated (to moved the ovum toward the
uterus) and partly non-ciliated
(secretory peg cells, nutritive to the
ovum).
B. Lamina propria: connective tissue rich
in blood vessels.
2. Musculosa: inner circular and outer
longitudinal smooth muscle fibers.
3. Serosa: areolar connective tissue
covered by simple squamous
mesothelium.
THE UTERUS
The Uterus
It is a thick-walled pear-shaped
organ which has a narrow lumen.
It is formed of body and cervix.
The body is formed of three layers:
1. Endometrium.
2. Myometrium.
3. Perimetrium.
The Endometrium
It is lined by simple columnar
epithelium.
Its lamina propria contains simple
tubular mucous glands lined by
columnar epithelium and may reach to
the myometrium.
It undergoes cyclic changes in
response to ovarian hormones.
It is divided into superficial layer
(stratum functionalis) and deep layer
(stratum basalis).
The Myometrium
Three layers of smooth muscle
fibers and connective tissue.
They are not easily distinguished
from each other.
The middle layer is called stratum
vascularis and contains numerous
large blood vessels.
During pregnancy, the smooth
muscle fibers increase in length.
The perimetrium
It is formed of areolar
connective tissue, blood
vessels and covered by
simple squamous
mesothelium.
Cyclic changes of the endometrium
1. Menstrual stage (from day 1
to day 5).
2. Proliferative phase (from day
6 to day 16).
3. Secretory phase (from day
17 to day 26).
4. Premenstrual stage (from
day 27 to day 28).
(1) Menstrual Stage
Due to hormonal deficiency specially
progesterone.
Constriction of coiled arteries for long
periods causes ischemia and rupture of
capillaries.
Glands fragment and uterine fluid,
tissue debris and blood are
sloughed out and discharged
through vagina.
Stratum functionalis is lost
(2) Proliferative Stage
Occurs during maturation of follicles till
ovulation.
Under the effect of estrogen secreted by the
follicles.
It is the stage of regeneration of the stratum
functionalis from stratum basalis.
Epithelium of basal glands recovers the raw
surface.
Glands increase in length, become straight
and uniform in diameter.
Endometrium increases in thickness from 0.5
mm to 2-3 mm.
(3) Secretory Stage
Related to the formation of corpus
luteum.
Under the effect of progesterone and
estrogen secreted by the luteal cells.
Endometrium becomes hypertrophied
and vascular to reaches its full thickness
(4-5 mm).
Endometrial glands become coiled (corkscrew).
The glandular lumen contains secretions
and rich in glycogen.
(4) Premenstrual Stage
Related to the involution of the corpus
luteum and formation of corpus albicans.
Spiral arteries undergo periodic constriction
leading to stasis in capillaries and periods
of ischemia.
Glands stop secretion leading to shrinkage
of stratum functionalis due to water loss.
The thickness of the endometrium
decreases.
Stratum functionalis appears deeply
stained because of the closely packed
stromal cells.
The Cervix
It consists of:
1. Endometrium:
– Epithelium: simple columnar mucoussecreting epithelium.
– Lamina propria: contains branched tubular
glands secreting mucous.
– The cervical endometrium does not change
during the menstrual cycle, only the amount
and consistency of the mucous chnge.
2. Myometrium: dense connective tissue and
few amount of smooth muscle fibers.
3. Adventitia: connective tissue (no peritoneum)
THE VAGINA
The Vagina
It consists of:
1. Mucosa:
– Epithelium: stratified squamous nonkeratinized epithelium rich in
glycogen.
– Lamina propria: contains lymphatic
nodules but no glands.
2. Musculosa: longitudinal muscle fibers
continuous with uterine muscles.
3. Adventitia: dense connective tissue.
MAMMARY GLANDS
Mammary Glands
It consists of lobes and lobules,
separated by septa formed of
dense connective tissue and
elastic fibers.
Fat tissue runs between lobes and
lobules.
Non-lactating gland (inactive): the
gland parenchyma is formed of
little amount of lactiferous ducts
only, with no alveoli.
Lactating Mammary Glands
Stroma: connective tissue septa and adipose
tissue are reduced.
Parenchyma: extensive system of secretory
alveoli budding from the ducts.
The alveoli are lined with simple cuboidal cells
with basal myoepithelial cells.
The intralobar ducts are lined with simple
cuboidal epithelium.
The main ducts are lined with stratified
squamous epithelium.
Mammary gland is an apocrine gland.
Prolactin stimulate secretion of milk.
Oxytocin stimulate ejection of milk.