The ovaries (female gonads) are two almond-
shaped glands suspended by ligaments in the up-
per pelvic cavity, one on either side of the uterus,
posterior and inferior to the fallopian tubes. Their
prime function is to produce the ova and the
female hormone estrogen and progesterone.
Although these hormones are manufactured by
the ovaries, their production is controlled by the
anterior pituitary gland. These hormones play
essential roles in the development of secondary
sex characteristics, the reproductive cycle, gesta-
tion, and lactation.
The graafiau follicles are microscopic pockets
in the ovaries. One a month, under hormonal in-
fluence, a follicle matures, ruptures, and expels
its ovum into the uterus. Each ovary normally
releases an ovum every 56 days, the right and left
ovary alternately discharging an ovum every 28
days. The menstrual cycle in most women is
therefore 28 days in length.
The fallopian (uterine) tubes are composed of
internal mucous, middle muscular, and outer
serous coats that are continuous with the layers
of the uterus. They serve as ducts of the ovaries,
providing a passageway to the uterus. These tubes
are in contact with the ovaries, but are not con-
tinuous with them. Their funnel-shaped openings,
called free openings, are fringed with fingerlike
processes that pick up an ovum and draw it into
the fallopian tubes, where it is transported to the
uterus by peristalsis and gravity. Fertilization of
an ovum normally takes place in the fallopian
The uterus (womb) is a hollow, pear-shaped
organ with thick, muscular walls. It is lined with
a specialized epitheliums, called endometrium,
which undergoes partial destruction about every
28 days in the nonpregnant woman.
The uterus averages 7 cm in length and 5 cm
in width. It has three openings: the openings of
the fallopian tubes laterally and the opening into
the vagina. The parts of the uterus are the body,
which is the large upper portion, and the cervix,
which is the smaller portion that projects into the
upper part of the vagina. The cervical opening
into the vagina is called the external os. The walls
of the uterus arc highly flexible and are composed
of three layers that are continuous with the respec-
tive layers of the fallopian tubes.
In addition to being the focal point of the en-
dometrial (menstrual) cycle, the uterus is the site
of implantation, growth, and development of the
fertilized ovum. The muscular walls of the uterus
produce powerful rhythmic contractions that are
important in the expulsion of the fetus at birth.
The vagina is a musculomembranous, collap-
sible tube capable of great distention. It is lined
with mucous membrane that extends from the cer-
vix to the vulva. The canal is about 7.5 cm long,
and its lining membrane, which is greatly folded,
is continuous with the inner lining of the uterus.
The vagina is the organ that receives the male
sperm during intercourse. It also forms the lower
portion of the birth canal, stretching widely dur-
ing delivery. In addition, it serves as an excretory
duct for uterine secretions and menstrual flow.
When females reach puberty, they begin to ex-
perience the two recurring female cycles, the
ovarian and endometrial.
As previously mentioned, each ovary produces
a mature ovum every 56 days. They expel their
ova on an alternating basis, approximately one
every 28 days. The length of this cycle may vary
markedly from individual to individual and be-
tween cycles of the same individual. On the first
days of menstruation, several ova within the
graafian follicles begin to mature, and normally
one will be expelled 14 days before the next
menstrual flow. This is the ovarian cycle.
The endometrial cycle centers around the
periodic development and breakdown of the en-
dometrial lining of the uterus. The first phase of
the cycle is the menses, or menstruation. It begins
when the endometrial lining starts to slough off
from the walls of the uterus, and it is characterized
by bleeding from the vagina. This is day 1 of the
cycle, and this phase usually lasts through day 5.
The time between the last day of the menses and
ovulation is known as the postmenstrual phase.
It lasts from day 6 through day 13 or 14 and is
characterized by proliferation of endometrial cells
in the uterus, which develop under the influence
of the hormone estrogen. Ovulation is the rup-
ture of a graafian follicle with the release of a
mature ovum into the fallopian tubes. It usu-
ally occurs on day 14 or 15 of the cycle. The