The Reproductive System
The Pelvis and Perineum

Pelvic wall is formed by
a. Pelvic girdle
b. Sacrum
c. Os coxae (ilium, ischium, and pubis)
The three os coxae bones (innominate
bones) come together to form the
ACETABULUM (hip socket).
 The PELVIC BRIM is a line that
separates the FALSE PELVIS (superior
to the brim) and the TRUE PELVIS
(inferior to the brim).

The pelvic inlet is also formed by the
PROMONTORY of the sacrum and a
line drawn to the pubic symphysis.
 The PELVIC OUTLET is formed by a line
from the inferior edge of the pubic
symphysis to the tip of the coccyx and
the plane extends laterally to the two
ISCHIAL TUBEROSITIES.

The pelvic inlet in females is wider than
deep.
 The male pelvic inlet is heart shaped.
 The outlet of the female is round while
on the male it is deeper than it is wide.
 In the female, the wide outlet leads to a
wide PUBIC ARCH.

Gender Differences in the Pelvis
MALE
CHARACTERISTIC
FEMALE
Less forward
Tilt
Far forward
Heavier
thickness
Lighter
Large, closer
together
Acetabulum
Small, farther
apart
Acute, 50-60
degrees
Pubic arch
Round, 80-90
degrees
Narrow, longer
sacrum
Wider, shorter
Narrow, heart
shaped
Pelvic inlet (brim)
Wider, oval
Narrow
Pelvic outlet
wider
There is no barrier that separates the
abdominal and pelvic cavities.
Therefore, intestines can drop into the
pelvis and the bladder and uterus
(females) can ascend into the abdomen.
 In males: RECTOVESICULAR POUCH
 In females: RECTOUTERINE POUCH

These pouches are sacs within the
posterior portions of the pelvic cavities.
Debris can accumulate in these cavities
and be a source of infection.
 The peritoneal fluids circulate within
these pouches.
 The bladder and uterus are outside the
peritoneum (retroperitoneal)

The PELVIC DIAPHRAGM
-muscular barrier across the pelvic outlet.
-prevents pelvic contents from falling out.
-LEVATOR ANI muscle (anterior)-raises the
anus
-COCCYGEUS muscle is posterior and
smaller

The EXTERNAL SPHINCTER ANI is voluntary
 The INTERNAL SPHINCTER ANI is
involuntary and part of the rectum.
 There is an opening in the levator ani
(urogential diaphragm) for the UROGENITAL
TRIANGLE and ARCH. This is where the
urogenital organs pass.
Reproduction


A species goal is to reproduce.
2 types:
1. ASEXUAL (without sex)
a. 1 partner
b. Parent and children are identical
2. SEXUAL
a. 2 cells combine (fertilization)
b. Children are similar but not identical to
parents.

Sex cells (sperm and egg) are made by
MEIOSIS. This form of cellular reproduction
reduces the number of chromosomes by half.
23 chromosomes per egg
23 chromosomes per sperm
46 chromosomes per zygote (fertilized egg)
Humans are SEXUALLY DIMORPHIC. There are two
distinct forms.
The primary sex organs are the TESTES (male) and
OVARIES (female). They produce sex cells called
gametes. They are also MIXED GLANDS.
In females, all meiosis is complete before birth-therefore,
all the eggs that will be present are there at birth.
They are dormant.
In males, meiosis begins at puberty. Therefore,
spermatozoa will be produced throughout the males
life from puberty to death.

The gonads (testes and ovaries) produce
hormones. They are endocrine glands.
1. Testosterone in males
2. Estrogen and Progesterone in
females

Sexual Accessory Organs help get the
gametes to where they have to go:
Males: tubules, penis
Females: vagina, uterus, cervix, oviducts
Secondary Sex Characteristics


Due to hormones.
Have nothing to do with reproduction.
They include:
1.
Facial and body hair
2.
Voice changes
3.
Mammary glands capable of milk production
4.
Increased musculature
5.
Shoulders, range of motion increase
6.
Increase in adipose tissue (fat) in female hip and buttocks
7.
Aggression increases
8.
Sex drive increases
THE MALE
Urine and semen both travel through the
same tube (urethra)
 There is a cord from the inguinal
ligament to the scrotum. This the
SPERMATIC CORD which contains
blood vessels, nerves, and vas deferens.

The URETERS from the kidneys lead to
the caudal end of the bladder. The
URETHRA passes caudally from the
bladder.
 A short distance down the urethra you
will find the PROSTATE GLAND. Inferior
to this gland is the ROOT of the penis.


SPERMATIC FASCIA is the covering for the spermatic
cord. The spermatic cord ends in a sac that contains
the testes.
 The testes are oval shaped. Which contain the
SEMINIFEROUS TUBULES.
 Remember, the testes begin in the abdominal cavity
and descend into the scrotum.
 As they descend, the inguinal ligament evaginates and
the spermatic fascia is formed form the aponeuroses
of the inguinal ligament.

The peritoneum lining the fascial sac is the
TUNICA VAGINALIS.
 Within the spermatic cord are muscle fibers
from the internal oblique muscle. This forms
the CREMASTER MUSCLE. When it
contracts, this muscle lifts the testicle. This is
important in maintaining an adequate
temperature for sperm production.
The scrotum is the outer skin and muscle
covering the testicles. The muscle within
the scrotum is the DARTOS MUSCLE.
 This muscle is responsible for wrinkling
the skin of the scrotum also helping in
keeping a stable, cooler temperature.

The EPIDIDYMIS is attached to the
testis. It has a head, body, and tail which
empties into the vas deferens.
 The testicle is covered by a “visceral”
layer called the TUNICA ALBUGINEA.

Internally, the testis has a network of
SEMINIFEROUS TUBULES which
combine to form a layer of ducts called
the RETE TESTIS. The VAS
EFFERENS are another layer that leads
to the epididymis.
 Sperm is stored in the epididymis

Whole Fetal Testis
The human (5 1/2 month fetal) testis is covered by a dense fibrous tunica
albuginea which contain developing blood vessels.
1 – seminiferous tubules
2 – sperm
3 – spermatid
4 – spermatocyte 2
5 – spermatocyte 1

Sperm finishes its development in the
epididymis-gains a tail and its shape is
streamlined.
 The head of the sperm contain enzymes that
dissolve the COROLLA of the ovum.
 The vas deferens connects to the SEMINAL
VESSICLES via the SEMINAL DUCT. After
this the vas deferens is called the
EJACULATORY DUCT.
Sperm
Identify the head, mid-piece, and tail. Notice the light
staining acrosome at the tip of the head
Penis
This cross section of the penis shows the
erectile tissues of both the corpus
spongiosum (lower right) and one of the
corpora cavernosa (upper left).



The urethra pass through the prostate gland and has
many fenestrations. The prostate dumps materials
into the semen through these holes. The ejaculatory
duct empties into the PROSTATIC URETHRA.
The prostatic urethra is connected to the
BULBOURETHRAL GLANDS or COWPER”S GLAND.
Here lubricants are added to the semen. After this
gland, the semen enters the PENILE URETHRA from
which it leaves the body.
The root of the penis is anchored to the body. The
root has a bulb in the enter and two wings (crura) on
either side.

The penis itself is made of three cylinders of
spongy tissue.
1. 2 corpus cavernosum
2. 1 corpus spongisoum
The spongiosum contains the penile urethra.
The spongy tissue in all three cylinders contain
spaces which become engorged with blood
during sexual arousal – erection.
These three cylinders compose the
BODY of the penis.
 The body ends in the GLANS.
 Erection is an PARASYMPATHETIC
response.
 Ejaculation is a SYMPATHETIC
response.

For Your Information…..

There are collagen fibers
that run on the outside
surface of the erectile tissue.
This collagen lies at right
angles to the circular fibers
in the shaft. This design is to
prevent the erect penis from
buckling or kinking during
intercourse.
Identify the Following:
Penis
bladder
Testicle
rectum
Epididymis
sacrum
Vas deferens
prostate gland
Ureter
bulbourethral gland
Urethra
seminal vessicle
Corpus spongiosum
seminal duct
Corpus cavernosum crus of penis
Glans
Scrotum
Pubic symphysis
THE FEMALE

In the female cat, cut through the pubic
symphysis. You will see a VESTIBULE. The
urethra empties into the vagina through the
UROGENITAL SINUS.
 In humans, the urethra empties into the
vestibule with the vagina.
 At the end of the vagina, you will see the
opening into the uterus. This is the CERVIX.
Vaginal
mucosa
Endocervical
opening
uterus



The UTERUS is a pear-shaped, muscular organ. This
is where a fertilized egg implants for development.
The inferior end of the uterus is called the INTERNAL
OS, which communicates with the cervix. The
EXTERNAL OS is the vaginal communication.
Superior to the uterus are the openings for the
OVIDUCTS. These tubes connect the uterus to the
OVARIES.
The end of the oviduct forms a funnel, or
INFUNDIBULUM. There is a space between the ovary
and infundibulum.

The cervix protrudes into the vaginal cavity.
Here it is called the FORNIX. It has an
anterior, posterior, and lateral section.
 The peritoneal cavity of the female is open as
the vagina ultimately leads to the
infundibulum. The peritoneal cavity of males
is closed. There is no entrance into the
abdomen from any male pelvic organ.

The GREATER VESTIBULAR GLANDS
(Bartholin’s Glands) are along the lateral
margin of the bulb of the vestibule. They
secrete a mucus substance for
lubrication during sexual intercourse.
Identify the Following:
Pubic symphysis
Sacrum
Clitoris
Labia
Linea alba
Uterus
Rectum
Anus
Vagina
Ovary
Oviduct
Infundibulum

After sperm is deposited into the vagina,
they must swim toward the cervix. After
entering the cervix, sperm must then find
their way to one of the oviduct.
Fertilization usually occurs in the distal
1/3 of the oviduct. The ZYGOTE (result
of fertilization) then travels back to the
uterus for implantation.
It takes 5 days for the zygote to reach
the uterus. By the time it reaches its
place of implantation, it is multicellular.
 At 6 weeks, you cannot distinguish
between a male and female zygote.
 DIFFERENTIATION-cells change to form
specific structures.

cleavage
morula
fertilization
fundus
ovum
blastocyst
Ovarian
ligament
ovary
body
implantation
fimbria
follicle
fornix
cervix
Cervical opening
Ovulation occuring
vagina
vagina
Ovary with corpus luteum
Here is the size of
the uterus in the
third trimester. Note
how it displaces the
bowel superiorly
and fills the lower
abdomen. (This
unfortunate woman
died accidentally,
and the baby died
too).

If the fetus is a male, the gonads will descend
along the GUBERNACULUM, through the
INGUINAL CANAL and the WOLFFIAN DUCT.
The MULLERIAN DUCT in a male becomes
associated with the kidney. If it is a female,
the MULLERIAN DUCT becomes the female
tube system. The gubernaculum becomes the
round ligments of the ovary and uterus
(female)
So, what happens to the embryonic
structures?
MALE
FEMALE
A small cord anchoring the
testis to the tunica vaginalis
Path of descent for embryonic
testis
Gubernaculum
Round ligament of uterus and
ovary
Associated with kidney and
forms part of urinary tract
Mullerian Duct
Female tube system
Tube system
Wollfian Duct
Associates with kidney and
becomes part of the urinary
system
There are small cilia attached to the
infundibulum and within the oviduct.
 These cilia push the egg (ovum) along
the length of the tube. The OVUM is the
largest cell in the body.


The peritoneum that extends to the ovary is
called the MESOVARIAN LIGAMENT.
 The mesentery to the uterus is the BROAD
LIGAMENT.
 The ROUND LIGAMENT of the ovary and the
ROUND LIGAMENT of the uterus both pass
through the broad ligament.
 The two round ligaments are remnants of the
GUBERNACULUM, an anchor for the ovaryuterus and uterus-inguinal ligament.

The following structures are HOMOLOGS
(structures that have same origin but different
functions in the two sexes)
Testes : ovaries
Oviduct : male urinary tract
Vas deferens : female urinary tract
The Perineum

Location: from the
pelvic diaphragm to
the skin.
 In reality: everything
from the external
genitals to the anus.
This includes skin,
arteries, fat, veins,
capillaries, nerves,
and lymphatics.
 It is divided into two
triangles:
a. Anterior
urogenital triangle
b. Posterior anal
triangle
If we were make a coronal section we
would see:
The urogenital diaphragm
- supports the urogenital structures
Superior to the UGD is the DEEP
PERINEUM. Inferior to the UGD is the
SUPERFICIAL PERINEUM.

If we expose the inferior surface of the
anterior urogenital triangle, we cannot
see the levator ani because it is covered
by the UGD.
 The bulb of the penis is anchored to the
UGD by the BULBOSPONGIOSUS
MUSCLE.

The crura (wings) of the penis are
anchored to the ischium by the
ISCHIOCAVERNOSUS MUSCLE.
 These muscles help to expel semen
during ejaculation.
 In the female, the perineum is diamond
shaped (as in the male)


The PERINEAL BODY extends and attaches to the
anal opening.
 An EPISIOTOMY is an incision into the perineal body
to prevent tearing during childbirth. An incision is
much easier healed than a tear.
 In the female, the bulb and crura (bulbocavernosus
and ischiocavernosus) come together to form the body
of the CLITORIS.
 The penis and clitoris are homologs.