C H A P T E R 3 9
Introduction to the reproductive system
597
T
he reproductive systems in males and females are
composed of the structures that support conception
and development of a fetus and the endocrine glands
that produce the hormones necessary for the regu-
lation and maintenance of these structures and that
facilitate reproduction. Though anatomically the two
systems appear to be very different, they have many
underlying similarities. The same fetal cells in males
and females give rise to the glands that produce sexual
hormones (gonads). In the female, those cells remain in
the abdomen and develop into the
ovaries
, the female
sexual glands. In the male, the cells migrate out of the
abdomen to form the
testes
(the male sexual glands),
which are suspended from the body in the scrotum. Both
male and female glands respond to follicle-stimulating
hormone (FSH) and luteinising hormone (LH), which
are released from the anterior pituitary in response
to stimulation from gonadotropin-releasing hormone
(GnRH) released from the hypothalamus.
FEMALE REPRODUCTIVE SYSTEM
The female reproductive system consists of two ovaries,
two fallopian tubes, the uterus and accessory structures,
including the vagina, clitoris, labia and breast tissue.
The hormones that stimulate and maintain these struc-
tures are oestrogen and progesterone. See Figure 39.1.
Structures
The ovaries are almond-shaped organs located on each
side of the pelvic cavity. The ovaries store the
ova
, or
eggs. Eggs contain half of the genetic material needed
to produce a whole cell. At birth, a female’s ovaries
contain all of the ova that a woman will have. No new
ova will ever be produced by the ovaries. The ova are
released into the abdomen throughout a woman’s life or
slowly degenerate over time. Each ovum is contained in
a storage site called a
follicle
; the follicles act as endo-
crine glands producing the hormones
oestrogen
and
progesterone
. The primary goal of these hormones is
to prepare the body for pregnancy and to maintain the
pregnancy until delivery.
Very near to each ovary is a fallopian tube. The
fallopian tube is a muscular tube with a ciliated lining
that is constantly moving. This movement propels the
ovum released into the abdomen down the fallopian
tube and into the
uterus
, or womb, for the developing
embryo and fetus. The uterus is a muscular organ that
can develop a blood-filled inner lining, or endometrium,
which allows for implantation of the fertilised egg and
supports the development of the placenta. The placenta
provides nourishment for the developing fetus and acts
as an endocrine gland producing the hormones needed
to maintain the active metabolic state of the pregnancy.
The muscular walls of the uterus are important for expel-
ling the developed fetus through the vagina at delivery.
Rectum
Bladder
Fallopian
tube Ovary
Uterus
Vagina
Labia
FIGURE 39.1
The female reproductive
system.
