Biology today

female reproductive system

• The female reproductive system consists of a pair of ovaries,
a pair of Fallopian tubes (oviducts), uterus, vagina, external
genitalia or vulva and breasts. a pair of breasts or mammary
glands are intergrated to it for child care. Out of these only
ovaries are primary sex organs. Oviducts, uterus, cervix and
vagina are female accessory ducts.

Fig.:Female reproductive system

Broad
ligament

Ligament

of ovary

Fundus

of uterus

Cavity

of uterus Isthmus Ampulla

Body

of uterus

Cervix

of uterus

Cervical canal

Fimbriae

Infundibulum

Vagina

Hymen

Ovary

Perimetrium

Myometrium

Endometrium

Internal os

External os

Vaginal opening

ovaries

• Ovaries are the primary sex organs in human female. They
are paired structures located in the upper pelvic cavity.

• Each ovary is held in place within peritoneal cavity by several
ligaments. The ovarian ligament anchors the ovary
medially to the uterus. The suspensory ligament anchors
it laterally to the pelvic wall and mesovarium suspends it
in between. Both suspensory ligament and the mesovarium
are parts of broad ligament which supports uterine tubes,
uterus and the vagina.

structure of the ovaries

• anatomically, it is differentiated into four parts–germinal
epithelium, tunica albuginea, cortex and medulla.
(i) Germinal epithelium is the outermost layer of the
ovary which is formed of simple squamous and cuboidal
cells. It forms oogonia in the foetus.
(ii) Tunica albuginea is poorly differentiated sheath of
dense connective tissue that lies below the germinal
epithelium and outside the cortex. Tunica albuginea
provides greyish colour to ovary.
(iii) Ovarian stroma consist of dense outer layer called
cortex and less dense inner portion the medulla.

• at birth, the ovaries contain an estimated total of 2 to 4
million oogonia (egg mother cells). No more oogonia are
formed and added after birth.

•    Only one ovarian follicle matures and ovulates in an adult

woman in every menstrual cycle, alternatively by the two

ovaries. So, only 450 of the total follicles mature during

the entire reproductive span. The rest of them degenerate

at different times. The degenerating process is called

follicular atresia. This is an example of programmed cell

death or apoptosis.

•    One result of this developmental pattern is that the eggs

ovulated near age 50 are 35 to 40 years older than those

ovulated just after puberty. It is possible that certain

chromosomal defects or abnormalities common among

children born to older women are the result of ageing

changes in the eggs.

follicular growth and atresis

follicular development

•    During foetal life, all the oogonia develop into primary

oocytes, which then begin a first meiotic division by

replicating their DNa. They do not, however, complete the

division in the fetus.

•    accordingly, all the eggs present at birth are primary oocytes

containing 46 chromosomes, each with two sister chromatids.

The cells are said to be in a state of meiotic arrest.

•    This state continues until puberty and the onset of renewed

activity in the ovaries.

Only those primary oocytes destined for ovulation complete

the first meiotic division which occurs just before the mature

follicle is ovulated. The second meiotic division occurs in

Fallopian tube after ovulation, but only if the secondary oocyte

is fertilised i.e., penetrated by a sperm.

•    The dormant primary oocyte, in the ovary of a newborn female,

is surrounded by a single layer of squamous follicular cells. This