Genital Organs in Male
This is the main
male organ of coitus. It is made of three bodies and covered
with skin. It varies in size from person to person, Its
normal length when in the flaccid condition is 7 to 11.5com
and 12 to 21 cms when erect.
The penis, the male
copulatory organ, is a cylindrical pendant organ located
anterior to the scrotum and functions to transfer sperm to
the vagina. The penis consists of three columns of erectile
tissue that are wrapped in connective tissue and covered
with skin. The two dorsal columns are the corpora cavernosa.
The single, midline ventral column surrounds the urethra and
is called the corpus spongiosum.
The penis has a
root, body (shaft), and glans penis. The root of the penis
attaches it to the pubic arch and the body is the visible,
pendant portion. The corpus spongiosum expands at the distal
end to form the glans penis. The urethra, which extends
throughout the length of the corpus spongiosum, opens
through the external urethral orifice at the tip of the
glans penis. A loose fold of skin, called the prepuce, or
foreskin, covers the glans penis.
tip of the penis
is known as glans. It is an expansion of the corpus
spongionum. The base of the glans projects out from the main
body of the penis and this projecting margin is called
This gland appears
to be a sexual organ, since in animals that have seasonal
sexuality, the prostate enlarges during the mating season
and then shrinks until the next. In the adult human male, it
is about 4cms across as its base and is the size of
chestnut. The prostate is composed of muscular and glandular
tissue. Its secretions pass down about 20 small ducts that
lead to the section of the Urethra that pierces the prostate
gland, but their purpose is not yet fully understood.
Smegma is mixture of
dead skin cells and skin grease and looks like soap as it
hides under the foreskin of the penis. In women it is found
near clitoris. The male reproductive system, like that of
the female, consists of those organs whose function is to
produce a new individual, i.e., to accomplish reproduction.
This system consists of a pair of testes, a network of
excretory ducts (epididymis, ductus deferens, and
ejaculatory ducts), seminal vesicles, the prostate, the bulb
urethral glands, and the penis.
The male gonads,
testes, or testicles, begin their development high in the
abdominal cavity, near the kidneys. During the last two
months before birth, or shortly after birth, they descend
through the inguinal canal into the scrotum, a pouch that
extends below the abdomen, posterior to the penis. Although
this location of the testes, outside the abdominal cavity,
may seem to make them vulnerable to injury, it provides a
temperature about 3°C below normal body temperature. This
lower temperature is necessary for the production of viable
sperm. The scrotum consists of skin and subcutaneous tissue.
A vertical septum, or partition, of subcutaneous tissue in
the center divides it into two parts, each containing one
testis. Smooth muscle fibers, called the dartos muscle, in
the subcutaneous tissue contract to give the scrotum its
wrinkled appearance. When these fibers are relaxed, the
scrotum is smooth. Another muscle, the cremaster muscle,
consists of skeletal muscle fibers and controls the position
of the scrotum and testes. When it is cold or a man is
sexually aroused, this muscle contracts to pull the testes
closer to the body for warmth.
Each testis is an
oval structure about 5 cm long and 3 cm in diameter. A
tough, white fibrous connective tissue capsule, the tunica
albuginea, surrounds each testis and extends inward to form
septa that partition the organ into lobules. There are about
250 lobules in each testis. Each lobule contains 1 to 4
highly coiled seminiferous tubules that converge to form a
single straight tubule, which leads into the rete testis.
Short efferent ducts exit the testes. Interstitial cells
(cells of Leydig), which produce male sex hormones, are
located between the seminiferous tubules within a lobule.
Sperm are produced
by spermatogenesis within the seminiferous tubules. A
transverse section of a seminiferous tubule shows that it is
packed with cells in various stages of development.
Interspersed with these cells, there are large cells that
extend from the periphery of the tubule to the lumen. These
large cells are the supporting, or sustentacular cells (Sertoli's
cells), which support and nourish the other cells.
Early in embryonic
development, primordial germ cells enter the testes and
differentiate into spermatogonia, immature cells that remain
dormant until puberty. Spermatogonia are diploid cells, each
with 46 chromosomes (23 pairs) located around the periphery
of the seminiferous tubules. At puberty, hormones stimulate
these cells to begin dividing by mitosis. Some of the
daughter cells produced by mitosis remain at the periphery
as spermatogonia. Others are pushed toward the lumen,
undergo some changes, and become primary spermatocytes.
Because they are produced by mitosis, primary spermatocytes,
like spermatogonia, are diploid and have 46 chromosomes.
spermatocytes goes through the first meiotic division,
meiosis I, to produce two secondary spermatocytes, each with
23 chromosomes (haploid). Just prior to this division, the
genetic material is replicated so that each chromosome
consists of two strands, called chromatids, that are joined
by a centromere. During meiosis I, one chromosome,
consisting of two chromatids, goes to each secondary
spermatocyte. In the second meiotic division, meiosis II,
each secondary spermatocyte divides to produce two
spermatids. There is no replication of genetic material in
this division, but the centromere divides so that a
single-stranded chromatid goes to each cell. As a result of
the two meiotic divisions, each primary spermatocyte
produces four spermatids. During spermatogenesis there are
two cellular divisions, but only one replication of DNA so
that each spermatid has 23 chromosomes (haploid), one from
each pair in the original primary spermatocyte. Each
successive stage in spermatogenesis is pushed toward the
center of the tubule so that the more immature cells are at
the periphery and the more differentiated cells are nearer
oogenesis in the female) differs from mitosis because the
resulting cells have only half the number of chromosomes as
the original cell. When the sperm cell nucleus unites with
an egg cell nucleus, the full number of chromosomes is
restored. If sperm and egg cells were produced by mitosis,
then each successive generation would have twice the number
of chromosomes as the preceding one.
The final step in
the development of sperm is called spermiogenesis. In this
process, the spermatids formed from spermatogenesis become
mature spermatozoa, or sperm. The mature sperm cell has a
head, midpiece, and tail. The head, also called the nuclear
region, contains the 23 chromosomes surrounded by a nuclear
membrane. The tip of the head is covered by an acrosome,
which contains enzymes that help the sperm penetrate the
female gamete. The midpiece, metabolic region, contains
mitochondria that provide adenosine triphosphate (ATP). The
tail, locomotor region, uses a typical flagellum for
locomotion. The sperm are released into the lumen of the
seminiferous tubule and leave the testes. They then enter
the epididymis where they undergo their final maturation and
become capable of fertilizing a female gamete.
begins at puberty and continues throughout the life of a
male. The entire process, beginning with a primary
spermatocyte, takes about 74 days. After ejaculation, the
sperm can live for about 48 hours in the female reproductive
The ductus deferens,
also called vas deferens, is a fibromuscular tube that is
continuous ( or contiguous) with the epididymis. It begins
at the bottom (tail) of the epididymis then turns sharply
upward along the posterior margin of the testes. The ductus
deferens enters the abdominopelvic cavity through the
inguinal canal and passes along the lateral pelvic wall. It
crosses over the ureter and posterior portion of the urinary
bladder, and then descends along the posterior wall of the
bladder toward the prostate gland. Just before it reaches
the prostate gland, each ductus deferens enlarges to form an
ampulla. Sperm are stored in the proximal portion of the
ductus deferens, near the epididymis, and peristaltic
movements propel the sperm through the tube.
The proximal portion of the ductus deferens is a component
of the spermatic cord, which contains vascular and neural
structures that supply the testes. The spermatic cord
contains the ductus deferens, testicular artery and veins,
lymph vessels, testicular nerve, cremaster muscle that
elevates the testes for warmth and at times of sexual
stimulation, and a connective tissue covering
deferens, at the ampulla, joins the duct from the adjacent
seminal vesicle (one of the accessory glands) to form a
short ejaculatory duct. Each ejaculatory duct passes through
the prostate gland and empties into the urethra.
The urethra extends
from the urinary bladder to the external urethral orifice at
the tip of the penis. It is a passageway for sperm and
fluids from the reproductive system and urine from the
urinary system. While reproductive fluids are passing
through the urethra, sphincters contract tightly to keep
urine from entering the urethra.
The male urethra is
divided into three regions. The prostatic urethra is the
proximal portion that passes through the prostate gland. It
receives the ejaculatory duct, which contains sperm and
secretions from the seminal vesicles, and numerous ducts
from the prostate glands. The next portion, the membranous
urethra, is a short region that passes through the pelvic
floor. The longest portion is the penile urethra (also
called spongy urethra or cavernous urethra), which extends
the length of the penis and opens to the outside at the
external urethral orifice. The ducts from the bulbourethral
glands open into the penile urethra.
The accessory glands
of the male reproductive system are the seminal vesicles,
prostate gland, and the bulbourethral glands. These glands
secrete fluids that enter the urethra.
The paired seminal
vesicles are saccular glands posterior to the urinary
bladder. Each gland has a short duct that joins with the
ductus deferens at the ampulla to form an ejaculatory duct,
which then empties into the urethra. The fluid from the
seminal vesicles is viscous and contains fructose, which
provides an energy source for the sperm; prostaglandins,
which contribute to the mobility and viability of the sperm;
and proteins that cause slight coagulation reactions in the
semen after ejaculation.
bulbourethral (Cowper's) glands are small, about the size of
a pea, and located near the base of the penis. A short duct
from each gland enters the proximal end of the penile
urethra. In response to sexual stimulation, the
bulbourethral glands secrete an alkaline mucus-like fluid.
This fluid neutralizes the
acidity of the urine residue in the urethra, helps to
neutralize the acidity of the vagina, and provides some
lubrication for the tip of the penis during intercourse.
Seminal fluid, or
semen, is a slightly alkaline mixture of sperm cells and
secretions from the accessory glands. Secretions from the
seminal vesicles make up about 60 percent of the volume of
the semen, with most of the remainder coming from the
prostate gland. The sperm and secretions from the
bulbourethral gland contribute only a small volume.
The volume of semen
in a single ejaculation may vary from 1.5 to 6.0 ml. There
are usually between 50 to 150 million sperm per milliliter
of semen. Sperm counts below 10 to 20 million per milliliter
usually present fertility problems. Although only one sperm
actually penetrates and fertilizes the ovum, it takes
several million sperm in an ejaculation to ensure that
fertilization will take place.
The male sexual
response includes erection and orgasm accompanied by
ejaculation of semen. Orgasm is followed by a variable time
period during which it is not possible to achieve another
Three hormones are
the principal regulators of the male reproductive system.
Follicle-stimulating hormone (FSH) stimulates
spermatogenesis; luteinizing hormone (LH) stimulates the
production of testosterone; and testosterone stimulates the
development of male secondary sex characteristics and
Genital Organs in Female
Breast is apparent
distinction between male and female. It is a mass of fatty
tissue. The main function of the breast is to produce milk
for the newborn baby. Breasts vary in size and shape. But
the shape and size of breasts has nothing to do with women
fertility and sexual desires. Breasts become slightly firm
during excitement. Whenever a woman feels lumps or bumps,
she should immediately consult a competent physician.
Situation of the
clitoris is on the front of pubic bone and is almost
surrounded by labia and consists of erectile tissues and
richly supplied with nerves. This is most sensitive parts of
the vulva. The size of the clitoris is 3/4 inch. The role of
clitoris in sex is still unknown, but it appears to be
involved in female excitement.
The name given to
female reproductive cell. They vary too much in size but
basically they have same shape. Egg is expelled from ovary
to fallopian tube, where it is fertilised by the male sperm,
otherwise it dies there within few days.
These tubes extend
from the ovaries that are situated on neither side of the
womb. Each is about 4" long. There is a free passage from
vagina to womb and womb to fallopian tubes.
It is the female
genital passage. Vagina ensheathe the penis during intercourse. It is made of modified skin, which covers an elastic
fibro vascular structure. From the opening it goes upwards
at the angle of 600-700. At the top cervix points in it. It
is approximate length is 10 CMS. The vagina undergoes active
changes during coitus.
This is a hollow,
muscular and thick walled organ connected with fallopian
tubes and it is pointed towards cervix. It is about 8 to 9
CMS in length, 6 CMS across in its widest part and about 4
CMS thick in the thickest part. The walls of the womb are
about 1 to 2 CMS thick and the length of the internal cavity
is about 7.5 to 8 CMS, measured from the external Os.