Hormone Regulation in Men
Spermatogenesis
• Spermatogenesis is the maturation process of spermatozoa.
Mature sperm are what is needed for sexual reproduction.
These mature sperm are also referred to as male gametes.
• The process must have the right conditions if healthy sperm
are to be produced. When the conditions are not ideal,
conceiving a child might be difficult or impossible.
• The process begins at puberty and continues uninterrupted
until death, unless there are medical conditions; however, as
men age, the amount of sperm one can produce typically
diminishes.
• Spermatozoa, produced by males,
contain a 23rd chromosome that is
either an X chromosome (female) or
Y chromosome (male), making each
sperm cell either female or male.
• Spermatozoa have a head that
contains a nucleus, a mid piece that
contains mitochondria, and a tail with
its end piece.
• Female spermatozoa have larger
heads than their male counterparts,
and are consequentially slower
swimmers.
• Spermatozoa “swim” by rotating a
tail, which allows them to come into
contact with the oocyte. One
spermatozoan fertilizes the egg,
thereby creating a zygote.
• Testes: In the male
reproductive system, sperm
are produced in the
seminiferous tubules of the
testes. The testes also
produce the male hormone
testosterone and a portion
of the seminal fluid, the
liquid in which sperm are
carried.
• Scrotum: The testes are two
organs contained in the
scrotum, an external sac in
the groin. The external
location of the scrotum
ensures the relatively low
temperature that is
necessary for the normal
development of sperm.
• Vas Deferens: After
formation, the sperm pass
from the testes into the
tubular epididymis, and
from there into another
passage, the vas deferens.
The Male Reproductive
System
• Penis: The first stage of the male
sexual act, erection, results from
nerve impulses from the autonomic
nervous system that dilate the
arteries of the penis, thus allowing
arterial blood to flow into erectile
tissues of the organ.
• Seminal Vesicle: The seminal
vesicle, which produces the seminal
fluid, and the prostate gland, which
produces the prostatic fluid, are both
connected to the ejaculatory duct
leading into the urethra.
• Semen: During sexual intercourse,
the ducts in the testes, epididymid,
and the ductus deferens cause
sperm to be pushed into the urethra,
and this mixes with the seminal and
prostatic fluids. The Cowper’s
glands also create mucus which is
added to this fluid, forming semen.
The semen travels through the
penile urethra during intercourse.
Hormone Regulation in Women
Oogenesis
• Oogenesis is the process whereby an ovum, or egg cell,
is created and matures. Mature ova are what is needed
for sexual reproduction. These mature ova are also
referred to as female gametes or mature oocytes.
• The process must have the right conditions if healthy
ovum are to be produced. When the conditions are not
ideal, conceiving a child may be difficult or impossible.
• The process begins at puberty and continues
uninterrupted until menopause, unless there are medical
issues.
• Ovary: There are two ovaries in
the female, held in place on each
side of the uterus by a
membrane; each ovary is about
the size of an almond. About
500,000 immature eggs are
present in the ovary at birth.
• Ovulation: Starting at puberty,
eggs mature successively, and
one breaks through the ovarian
wall about every 28 days (known
as ovulation or the ovarian cycle),
which continues until
menopause, or cessation of
reproductive functioning in the
female.
• Ovum: The name for the egg
which the ovary releases at least
once every 28 days.
• Fallopian Tubes: After its release
from the ovary, the ovum passes
into the oviduct (uterine or
fallopian tube) and into the
uterus.
The Female Reproductive
System
• Uterus: The human uterus is pearshaped and about 3 in. (7.6 cm) long
(it expands greatly during
pregnancy); it normally lies in the
pelvis, where it is supported by a
ligament on either side extending to
the pelvic wall. The body of the
uterus tapers down to a necklike
structure (cervix) that leads into the
vagina.
• Vagina: The vagina, a passage
connecting the uterus with the
external genitals, receives the penis
and the sperm ejaculated from it
during sexual intercourse. It also
serves as an exit passageway for
menstrual blood and for the baby
during birth.
• Vulva: These are the external
genitals, including the clitoris
(erectile tissue that responds to
sexual stimulation), and the labia,
which are composed of elongated
folds of skin.
Fertilization
• If the ovum is fertilized by the sperm, pregnancy occurs.
The fertilized ovum travels from the fallopian tubes into
the uterus, where it becomes implanted in the lining of
that organ, also known as the endometrium. If
fertilization does not occur, the ovum and the lining of the
uterine wall pass out of the body through the vagina
(during the menstrual cycle). Endometrial tissues then
build up again in the uterus in anticipation of the next
release of an ovum.
• If the ovum is fertilized, and the embryo (fertilized ovum)
implants in the tube, or another area outside the uterus,
an ectopic pregnancy occurs. Surgery is required to
remove the fetus.
Puberty
• Puberty can take anywhere from one to six years to occur. There is no “right”
time for it to start– each person is different. In girls, it typically starts between
the ages of 9 to 14, while for the boys, it seems to start at 10 to 17.
• What triggers puberty is the hormones that your brain is releasing. When
your body gets closer to sexual maturity, the pituitary gland begins to release
estrogen and progesterone for the girls and testosterone for the boys. This
helps each gender’s reproductive organs to develop.
• Your body also has growth hormones running through it. This affects your
height, weight, and overall shape. Girls seem to get curvier, while boys tend
to get more muscular and broad-shouldered.
• Typical physical changes that both sexes see are hair growth, acne, change
in voice, and sweating.
• Hormones also affect the sexes in emotional ways. You may begin to
overreact, be overly emotional, quick-tempered, depressed, or you may
begin to experience mood swings that you haven’t had before. It’s important
that if you start to feel as though you are losing control, you speak to a
trusted adult or health care professional.