UTERUSUTERUS

Is a pear shaped Is a pear shaped organ.organ.

consist of consist of 1.1. Body.Body.2.2. lower cylindrical part lower cylindrical part

called cervix called cervix 3.3. the dome shaped part the dome shaped part

of the body above the of the body above the openings of uterine openings of uterine tubes called fundus.tubes called fundus.

The wall of the uterus is The wall of the uterus is

relatively thick and consist of relatively thick and consist of

three layers:three layers:

serosa or adventitiaserosa or adventitia: the outer : the outer

most layer.most layer.

myometeriummyometerium : thick layers of : thick layers of

smooth muscles.smooth muscles.

endometriumendometrium: the inner layer : the inner layer

of mucosa of uterus.of mucosa of uterus.

The fundus and the body of The fundus and the body of

the uterus have the same the uterus have the same

histological features which histological features which

differ than that of the cervix.differ than that of the cervix.

MYOMERTRIUM:MYOMERTRIUM:

Composed of bundles of Composed of bundles of

smooth muscle fibers smooth muscle fibers

separated by connective separated by connective

tissues .tissues .

they form four poorly defined they form four poorly defined

layers .layers .

the the 1st and the 4th1st and the 4th layers are layers are

longitudinally arranged longitudinally arranged

(parallel to the axis of the (parallel to the axis of the

uterus ) uterus )

while the while the middle two layersmiddle two layers are are

irregular and contain the larger irregular and contain the larger

blood vessels.blood vessels.

During pregnancy the myometrium increase greatly in its proportion During pregnancy the myometrium increase greatly in its proportion

both due to both due to hyperplasiahyperplasia (increase in number of smooth muscle cells) (increase in number of smooth muscle cells)

and and hypertrophy hypertrophy (increase in cells size).(increase in cells size).

During pregnancy those smooth muscle cells have the character of During pregnancy those smooth muscle cells have the character of

protein secreting cells and they synthesis collagen leading to protein secreting cells and they synthesis collagen leading to

significant increase in collagen content of the uterus .significant increase in collagen content of the uterus .

After pregnancy some smooth muscle cells will be destructed and After pregnancy some smooth muscle cells will be destructed and

others will decrease in size with enzymatic degradation of collagen others will decrease in size with enzymatic degradation of collagen

and so the uterus will return to its prepregnancy size.and so the uterus will return to its prepregnancy size.

ENDOMETRIUM:ENDOMETRIUM:

Consist of epithelium and lamina propria Consist of epithelium and lamina propria

containing simple tubular uterine glands.containing simple tubular uterine glands.

The epithelium consist of a mixture of The epithelium consist of a mixture of

ciliated and secretory columnar cells .ciliated and secretory columnar cells .

The epithelium that line the uterine glands The epithelium that line the uterine glands

is similar to the surface epithelium of the is similar to the surface epithelium of the

uterus however ciliated cells are rare within uterus however ciliated cells are rare within

the glands .the glands .

Connective tissue lamina propria is rich in Connective tissue lamina propria is rich in

fibroblasts with abundant ground surface .fibroblasts with abundant ground surface .

The endmetrium can be divided in to The endmetrium can be divided in to

layers:layers:

stratum basalisstratum basalis: the deepest layer : the deepest layer

adjacent to the myometrium it consist adjacent to the myometrium it consist

of lamina propria and the beginnings of lamina propria and the beginnings

of the uterine glands.of the uterine glands.

stratum functionalisstratum functionalis: contain the : contain the

remaining parts of the lamina propria remaining parts of the lamina propria

uterine glands and covered by surface uterine glands and covered by surface

epithelium , this layer undergo epithelium , this layer undergo

profound changes during the profound changes during the

menstrual cycle while the basalis menstrual cycle while the basalis

layer remain unchanged.layer remain unchanged.

The blood vessels supplying the endometrium The blood vessels supplying the endometrium

are very important , the arcuate arteries are are very important , the arcuate arteries are

found within the myometrium they give 2 sets of found within the myometrium they give 2 sets of

arteries:arteries:

straight arterioles: supplying stratum basalis.straight arterioles: supplying stratum basalis.

Spiral arterioles: supplying stratum functionalisSpiral arterioles: supplying stratum functionalis

MENSTRUAL CYCLE:MENSTRUAL CYCLE:

After puberty the ovarian hormones (After puberty the ovarian hormones (estrogen and progesteroneestrogen and progesterone ) which ) which

are under stimulus of the anterior lobe of pituitary causes the endometrium are under stimulus of the anterior lobe of pituitary causes the endometrium

to undergo cyclical structural changes during the menstrual cycle.to undergo cyclical structural changes during the menstrual cycle.

The average of each cycle is about 28 days , day one of the cycle is taken The average of each cycle is about 28 days , day one of the cycle is taken

as the day when the menstrual bleeding begins. The menstrual discharge as the day when the menstrual bleeding begins. The menstrual discharge

consist of degenerating endometrium mixed with blood from the ruptured consist of degenerating endometrium mixed with blood from the ruptured

blood vessels .blood vessels .

The menstrual phase lasts for 3-4 days on average . The next phases of the The menstrual phase lasts for 3-4 days on average . The next phases of the

cycle are called the proliferative and secretory phases.cycle are called the proliferative and secretory phases.

Proliferative phase (follicular, estrogen phase)Proliferative phase (follicular, estrogen phase)

Begins after the menstrual phase and its duration is variable (usually last Begins after the menstrual phase and its duration is variable (usually last

from day 5 to day 15 or 16 ) .from day 5 to day 15 or 16 ) .

At its beginning the uterine mucosa are relatively thin (0.5mm) and it At its beginning the uterine mucosa are relatively thin (0.5mm) and it

coincides with rapid growth of small group of ovarian follicles which start coincides with rapid growth of small group of ovarian follicles which start

secreting increasing amount of estrogen .secreting increasing amount of estrogen .

Estrogen hormone will have its effect on the endometrium so it will Estrogen hormone will have its effect on the endometrium so it will

enhance cellular proliferation and induce rebuilding of the endometrium enhance cellular proliferation and induce rebuilding of the endometrium

lost during menstruation .lost during menstruation .

Proliferative phase (follicular, estrogen phase)Proliferative phase (follicular, estrogen phase)

During this phase the During this phase the endometrium is covered by a endometrium is covered by a simple columnar epithelium.simple columnar epithelium.

The glands also formed of The glands also formed of simple columnar cells and simple columnar cells and they are straight tubules with they are straight tubules with narrow lumen.narrow lumen.

At the end of the proliferative At the end of the proliferative phase the endometrium is 2-3 phase the endometrium is 2-3 mm thick.mm thick.

Secretory phase (luteal phase):Secretory phase (luteal phase):

It starts after ovulation under effect of progesterone secreted from the corpus luteum. It starts after ovulation under effect of progesterone secreted from the corpus luteum.

Progesterone secretion will stimulate further growth of the uterine glands where they become Progesterone secretion will stimulate further growth of the uterine glands where they become

highly coiled & their lumen will be filled with glycoprotein secretion.highly coiled & their lumen will be filled with glycoprotein secretion.

In this phase the endometrium reach its maximum thickness which is about 5mm. due to In this phase the endometrium reach its maximum thickness which is about 5mm. due to

accumulation of secretion & edema in the stroma.accumulation of secretion & edema in the stroma.

If fertilization occur the embryo will reach the uterus during its secretory phase & it is If fertilization occur the embryo will reach the uterus during its secretory phase & it is

thought that the secretion of the gland is the major source of nutrition for the embryo before thought that the secretion of the gland is the major source of nutrition for the embryo before

its implantation .its implantation .

Proesterone hormone will also inhibits the contraction of the smooth muscle cells of the Proesterone hormone will also inhibits the contraction of the smooth muscle cells of the

myometrium that might otherwise interfere with the implantation of the embryo.myometrium that might otherwise interfere with the implantation of the embryo.

Menstrual phase :Menstrual phase :

If fertilization does not occur the corpus luteum only programmed to act for 10-12 days after ovulation . If fertilization does not occur the corpus luteum only programmed to act for 10-12 days after ovulation .

After that marked decrease in estrogen & progesterone levels occur causing contraction of the spiral After that marked decrease in estrogen & progesterone levels occur causing contraction of the spiral

arterioles supplying struatum functionalis. Immediately prior to menstruation the endometrium regress, arterioles supplying struatum functionalis. Immediately prior to menstruation the endometrium regress,

endometrial venous drainge is inhibited & an intense vasoconstriction of the spiral arterioles followed by endometrial venous drainge is inhibited & an intense vasoconstriction of the spiral arterioles followed by

vaso-relaxation is generated. vaso-relaxation is generated.

These events leads to tissue ischemia These events leads to tissue ischemia

& damage, with shedding of the & damage, with shedding of the

stratum functionalis & bleeding occur stratum functionalis & bleeding occur

from fragments of arterioles from fragments of arterioles

remaining in the stratum basalis.remaining in the stratum basalis.

Menstruation cease as the damaged Menstruation cease as the damaged

spiral arterioles vasoconstrict & the spiral arterioles vasoconstrict & the

endometrium regenerate.endometrium regenerate.

Later repair of the endometrium & Later repair of the endometrium &

new blood vessels formation lead to new blood vessels formation lead to

complete cessation of bleeding within complete cessation of bleeding within

5-7 days from the start of the 5-7 days from the start of the

menstrual cyclemenstrual cycle

Full term placenta:Full term placenta:

At full term, the placenta is discoid in At full term, the placenta is discoid in

shape with a diameter of 15-25 cm.shape with a diameter of 15-25 cm.

It approximately 2-3cm. in thickness& It approximately 2-3cm. in thickness&

about 500-600gm. in weight.about 500-600gm. in weight.

The placenta has two surfaces: The placenta has two surfaces:

aa fetal surfacefetal surface which is very smooth, which is very smooth,

in contact with fetus in contact with fetus

a a maternal surfacematernal surface which is rough, which is rough,

irregular & in contact with wall of the irregular & in contact with wall of the

uterus, it consist of about 15-20 uterus, it consist of about 15-20

polygonal areas, which are known as polygonal areas, which are known as

cotyledons. cotyledons.

The formation of the placenta is fully established by The formation of the placenta is fully established by

the end of the fourth month.the end of the fourth month.

The human placenta has a complex villous structure The human placenta has a complex villous structure

that greatly increases the contact surface area between that greatly increases the contact surface area between

maternal blood & fetal capillaries so giving greater maternal blood & fetal capillaries so giving greater

nutritional support for the fetus.nutritional support for the fetus.

The umbilical cordThe umbilical cord

The umbilical cord The umbilical cord connects the body of the fetus to connects the body of the fetus to

the placental disc.the placental disc.

It is formed of two umbilical arteries & one umbilical It is formed of two umbilical arteries & one umbilical

vein supported by loose gelatinous connective tissue vein supported by loose gelatinous connective tissue

called Wharton’s jelly.called Wharton’s jelly.

THE FETAL PART OF PLACENTA:THE FETAL PART OF PLACENTA:

consists ofconsists of a a chorionic plate & chorionic plate &

branching processes or villi, which branching processes or villi, which

arise from it.arise from it.

These chorionic villi are the basic These chorionic villi are the basic

functional units of the placenta. functional units of the placenta.

The villi that arise from the chorionic The villi that arise from the chorionic

plate are usually called plate are usually called stem villistem villi,,

those villi that are attached to the those villi that are attached to the

basal plate are basal plate are anchoring villi,anchoring villi, and and

those villi which ends free in the those villi which ends free in the

intervillous spaces are the intervillous spaces are the terminal terminal

villivilli..

Villi are alike histologically.Villi are alike histologically.

In each villous there is a fetal In each villous there is a fetal

capillary lined with endothelium & is capillary lined with endothelium & is

contained in the loose connective contained in the loose connective

tissue core of the villous. tissue core of the villous.

IN the core there are a few bundles of IN the core there are a few bundles of

collagen fibers & fibroblasts also collagen fibers & fibroblasts also

some scattered smooth muscle fibers. some scattered smooth muscle fibers.

Larger cells with large eccentric Larger cells with large eccentric

spherical nuclei (cells of Hofbauer) spherical nuclei (cells of Hofbauer)

are also present; possibly these are are also present; possibly these are

phagocytic cells.phagocytic cells.

The trophoblast cells covering The trophoblast cells covering

each villous consists of two well each villous consists of two well

defined layers defined layers cytotrophoblasts & cytotrophoblasts &

syncytiotrphoblastsyncytiotrphoblast

until approximately the middle of until approximately the middle of

the third month of the pregnancy, the third month of the pregnancy,

the cytotrophoblast layer will the cytotrophoblast layer will

progressively disappear until at progressively disappear until at

term only a few isolated clumps term only a few isolated clumps

of cells are left.of cells are left.

The cytotrophoblast layer: The cytotrophoblast layer: (langhan’s cells)(langhan’s cells)

consist of large, pale cells.consist of large, pale cells.

In early stages of pregnancy these cells form a In early stages of pregnancy these cells form a

complete layer between syncytial cells & the complete layer between syncytial cells & the

basement membrane. basement membrane.

The nuclei of these cells were large & rounded The nuclei of these cells were large & rounded

with high nucleo-cytoplasmic ratio.with high nucleo-cytoplasmic ratio.

In mature placenta langhan’s cells don’t form a In mature placenta langhan’s cells don’t form a

complete layer, their number decrease greatly, complete layer, their number decrease greatly,

but they could still be recognized. but they could still be recognized.

Cytotrophoblasts cells function mainly as stem Cytotrophoblasts cells function mainly as stem

cells for the overlying syncytiotrphoblasat.cells for the overlying syncytiotrphoblasat.

The syncytiotrphoblasat layer:The syncytiotrphoblasat layer:

is a dark variably thick layer.is a dark variably thick layer.

in which numerous small in which numerous small

nuclei are found & no nuclei are found & no

intercellular boundaries can be intercellular boundaries can be

distinguished.distinguished.

This layer becomes This layer becomes

progressively thinner through progressively thinner through

out pregnancy.out pregnancy.

The maternal part of the placentaThe maternal part of the placenta

is formed by the decidua basalis, is formed by the decidua basalis,

which consist chiefly of the which consist chiefly of the

connective tissue stroma, the cells connective tissue stroma, the cells

of which are decidual in nature. of which are decidual in nature.

The endometrial cells become The endometrial cells become

large, polygonal & rich in glycogen large, polygonal & rich in glycogen

& lipid droplets. & lipid droplets.

Endometrial glands, fibrinoid Endometrial glands, fibrinoid

substance, & small clumps of substance, & small clumps of

trophoblastic cells are also trophoblastic cells are also

present. present.

In the initial placenta, the In the initial placenta, the

placental barriers between fetal & placental barriers between fetal &

maternal circulations are maternal circulations are

composed of 4 layers: composed of 4 layers:

(a) the endothelial lining of the (a) the endothelial lining of the

fetal vessels fetal vessels

(b) the connective tissue in the (b) the connective tissue in the

villous core villous core

(c) the cytotrophoblastic layer (c) the cytotrophoblastic layer

(d) the syncytium. (d) the syncytium.

From the fourth month From the fourth month

onward the placental onward the placental

barriers are formed only barriers are formed only

from the endothelial lining from the endothelial lining

of fetal vessels and the of fetal vessels and the

syncytium. This will greatly syncytium. This will greatly

increase the rate of increase the rate of

exchange through them.exchange through them.