Reproductive system

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Human Anatomy
The Reproductive System

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Comparison of the Female and
Male Reproductive Systems
 Female typically produces and releases
a single oocyte monthly.
 Male produces 100,000,000’s of
(sperm) daily.
 male gametes are stored for a short
time
 if they are not expelled from the body
within that period, they are resorbed

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Anatomy of the Male
Reproductive System
 Internal organs: testes, spermatic
cord, ductus deferens, seminal
glands, prostate.
 External organs include:
 The penis
 The scrotum
 The male urethra

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Testes
 Small, oval organ
 Housed in the scrotum
 Produces:
 Sperm

Androgens (testosterone).
 Coverings
 Serous membrane called tunica vaginalis

Parietal layer

Visceral layer.
 Tunica albuginea

Forms internal septa

250 lobules per testis
 Each lobule has up to 4 seminiferous
tubules

Two types of cell

Sustentacular cells

Germ cells
 Interior is called mediastinum testis.

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Testes
 Sperm develop in the semineferous tubules
 Interstitial spaces: surround the seminiferous tubules.
 Contain interstitial (Leydig) cells

produce hormones called androgens.
 Several types of androgens
 most common one is testosterone.
 the adrenal cortex secretes a small amount of androgens
 the vast majority of androgen release is via interstitial
cells in the testis
 These hormones cause males to develop the classic
characteristics:

axillary and pubic hair

deeper voice

sperm production.

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Testes
 Series of tubes:
 Seminiferous
tubules
 Straight ducts
 Rete testis
 Efferent ductule
 Epididymis
 Ductus deferens

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The testicular tunicsThe testicular tunics
1- testis; (orchis)
2- epididymis
3- ductus deferens
4- tunica vaginalis testis
5- cavum vaginalis testis
6- fascia spermatica
interna
7- m. cremaster
8- fascia cremasterica
9- fascia spermatica
externa
10-tunica dartos
11-cutis

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Spermatic Cord
 The blood vessels
and nerves to the
testis travel from
within the abdomen
to the scrotum in a
multilayered
structure called the
spermatic cord.

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Developmemt of sperm
 Called spermatogenesis
 Occurs in the seminiferous tubules
 Process:
 Spermatogonium
 Primary spermatocyte
 Secondary spermatocyte
 Spermatid
 Spermiogenesis
 Spermatid matures into spermatozoon

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Epididymis
 The epididymis is a comma-shaped structure composed of
an internal duct and an external covering of connective
tissue.
 Its head lies on the superior surface of the testis, while the
body and tail are posterior to the testis.
 Internally, the epididymis contains a long, convoluted duct
of the epididymis, which is approximately 4 to 5 meters in
length.
 Sperm must reside in the epididymis for a period of time to
become mature and fully motile.
 If they are expelled too soon, they lack the motility
necessary to travel through the female reproductive tract
and fertilize an oocyte.
 If sperm are not ejected from the male reproductive system
in a timely manner, the old sperm degenerate in the
epididymis.

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Ductus Deferens
 When sperm leave the epididymis,
they enter the ductus deferens,
also called the vas deferens.
 The ductus deferens is a thick-
walled tube that travels within the
spermatic cord, through the
inguinal canal, and within the
pelvic cavity before it reaches the
prostate gland.
 The ampulla of the ductus
deferens unites with the proximal
region of the seminal vesicle to
form the terminal portion of the
reproductive duct system, called
the ejaculatory duct.

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1 -1 - lobula testislobula testis
2 -2 - septula testisseptula testis
3 -3 - tubuli seminiferitubuli seminiferi
contorticontorti
4 -4 - tubuli seminiferi rectitubuli seminiferi recti
5 -5 - rete testisrete testis
6 -6 - ductuli efferentesductuli efferentes
testistestis
7 -7 - ductus epididymidisductus epididymidis
8 -8 - ductus deferensductus deferens
9 -9 - canalis inguinaliscanalis inguinalis
10 -10 - vesicula seminalisvesicula seminalis
11 -11 - ductus excretoriusductus excretorius
12 -12 - ductus ejaculatoriusductus ejaculatorius

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Urethra
 Transports semen from the
ejaculatory duct to the outside of
the body.
 Subdivided into:
 prostatic urethra that extends
through the prostate gland
 membranous urethra that
travels through the urogenital
diaphragm
 penile urethra that ends
through the penis
 Sperm leave the body through
the urethra.

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Accessory Glands
 The vagina has a highly acidic environment to prevent bacterial
growth.
 Sperm cannot survive in this type of environment, so an alkaline
secretion called seminal fluid is needed to lessen the acidity of the
vagina and bring pH values closer to neutral.
 As the sperm travel through the reproductive tract (a process that can
take several days), they are nourished by nutrients within the seminal
fluid.
 The components of seminal fluid are produced by accessory glands:
 seminal vesicles
 prostate gland
 bulbourethral glands

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Seminal Vesicles
 The paired seminal vesicles are located on the posterior surface
of the urinary bladder adjacent to the ampulla of the ductus
deferens.
 Each seminal vesicle is an elongated, pouchlike hollow organ
approximately 5–8 centimeters long.
 It is the proximal portion of each seminal vesicle that merges
with a ductus deferens to form the ejaculatory duct.
 The seminal vesicles secrete a viscous, whitish-yellow alkaline
fluid containing both fructose and prostaglandins.
 The fructose is a sugar that nourishes the sperm as they travel
through the female reproductive tract, while the prostaglandins
promote the widening and slight dilation of the external os of the
cervix.

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Prostate Gland
 A compact encapsulated organ that weighs about 20 grams and
is shaped like a walnut, measuring approximately 2 cm by 3 cm
by 4 cm.
 Located immediately inferior to the bladder.
 Secretes a slightly milky fluid that is weakly acidic and rich in
citric acid, seminalplasmin, and prostate-specific antigen (PSA).
 citric acid is a nutrient for sperm health
 seminalplasmin is an antibiotic that combats urinary tract
infections
 PSA acts as an enzyme to help liquefy semen following
ejaculation

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Bulbourethral Glands
 Paired, pea-shaped
 Also called Cowper’s glands
 Location:
 within the urogenital diaphragm
 on each side of the membranous urethra.
 Each gland has a short duct
 projects into the base of the penis
 enters the spongy urethra.
 secretory product
 clear, viscous mucin (forms mucus when mixed with water).

mucin protects the urethra

serves as a lubricant during sexual intercourse.

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Scrotum
a skin-covered sac that houses:

male gonads

first portion of the duct system
 Testes exposed to elevated temperatures
 Skin of the scrotal sac becomes thin
 The cremaster muscle relaxes
 The testes temperature becomes less than normal
body temperature.
 The opposite occurs if the testes are exposed
to cold.

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Semen
 Combination of seminal fluid from the
accessory glands and sperm.
 Called the ejaculate (when released during
ejaculation)
 normally about 3 to 5 milliliters
 contains approximately 200 to 500 million
spermatozoa.
 Average transit time: about 2 weeks
 from release of sperm into the lumen of the
seminiferous tubules, passage through the duct
system, and appearance in the ejaculate.

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Anatomy of the Female
Reproductive System
INTERNAL organs of the female are:
the ovaries, uterine tubes, vagina
EXTERNAL organs comprise the
strructures associated with the
pudendal cleft

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Ovary (ovarium, oophoron)
 The principal gland of female genial system,
which produces the oocytes and hormones
(estrogen and progesterone)
 It is a paired flattend ovoid organ sized 1x2x3
cm
 The principal substance of ovary is divided
into the ovarian cortex and ovarian medulla

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Ovarian Follicles
 Within the cortex are
thousands of ovarian
follicles.
 Several different kinds of
ovarian follicles, each
representing a different
stage of development.
 Oogenesis:
 maturation of a primary
oocyte to a secondary
oocyte.

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Before Birth
 The process of oogenesis occurs in a female fetus
before birth. At this time, the ovary contains
primordial germ cells called oogonia, which are
diploid cells, meaning they have 23 pairs of
chromosomes.
 During the fetal period, the oogonia start the process
of meiosis, but they are stopped at prophase I. At
this point, the cells are called primary oocytes.
 At birth, the ovary of a female child is estimated to
contain approximately 1.5 to 2 million primordial
follicles within its cortex.
 The primary oocytes in the primordial follicles remain
arrested in prophase I until after puberty.

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From Puberty to Menopause
 During childhood ovaries are inactive, and no follicles
develop.
 Atresia occurs, in which some primordial follicles
regress or break down.
 By the time she reaches puberty only about 400,000
primordial follicles remain.
 At puberty, the hypothalamus releases GnRH
(gonadotropin-releasing hormone), which stimulates
the anterior pituitary to release FSH (follicle-
stimulating hormone) and LH (luteinizing hormone).
 The levels of FSH and LH vary in a cyclical pattern
and produce a monthly ovarian cycle.
 The three phases of the ovarian cycle: are the
follicular phase, ovulation, and the luteal phase.

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The Three Phases of the Ovarian Cycle
 Follicular phase occupies days 1–13 of an approximate 28-
day ovarian cycle.
 Ovulation occurs on day 14 of a 28-day ovarian cycle and is
defined as the release of the secondary oocyte from a
vesicular follicle.
 only one ovary ovulates each month
 Luteal phase occurs during days 15–28 when the remaining
follicle cells in the ruptured vesicular follicle turn into a
corpus luteum.
 secretes progesterone and estrogen that stabilize and
build up the uterine lining, and prepare for possible
implantation of a fertilized oocyte
 has a life span of about 10–13 days if the secondary
oocyte is not fertilized
 it regresses and becomes a corpus albicans
 the uterine lining to be shed as menstruation

menarche

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Regions of the Uterus
 Fundus
 Body
 Isthmus
 Cervix
 Cervical canal
 Internal ostium
 External ostium

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Wall of the Uterus
 Composed of three concentric tunics:
 Perimetrium
 Myometrium
 Endometrium
 The outer tunic of most of the uterus is a serosa called the
perimetrium.
 continuous with the broad ligament
 The myometrium is the thick, middle tunic of the uterine wall
formed from three intertwining layers of smooth muscle.
 in the nonpregnant uterus, the muscle cells are less than
0.25 millimeters in length
 during the course of a pregnancy, smooth muscle cells
increase both in size and in number

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The Uterus Serves Four
Functions
 Site for implantation.
 pre-embryo implants into the inner uterine wall and becomes
connected to the uterine lining
 Supports, protects, and nourishes the developing embryo/fetus
 forms a vascular connection with the mother’s uterine wall
that later develops into the placenta
 Ejects the fetus at birth after maternal oxytocin levels increase
to initiate the uterine contractions of labor.
 Site for menstruation.
 if an oocyte is not fertilized or after a baby is expelled, the
muscular wall of the uterus contracts and sheds its inner
lining as menstruation

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After Menopause
 The time when a woman is nearing menopause is called
perimenopause.
 estrogen levels begin to drop, and
 a woman may experience irregular periods, skip some periods, or
have very light periods
 When a woman has stopped having monthly menstrual
cycles for 1 year and is not pregnant, she is said to be in
menopause.
 The age at onset typically is between 45 and 55 years
 follicles stop maturing, and significant amounts of estrogen and
progesterone are no longer being secreted
 a woman’s endometrial lining does not grow, and she no longer has
a menstrual period

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Uterine Tubes
 The uterine tubes, also called the fallopian tubes or oviducts,
extend laterally from both sides of the uterus toward the ovaries.
 In these tubes, the secondary oocyte is fertilized, and the pre-
embryo begins to develop as it travels toward the uterus.
 Usually it takes the pre-embryo about 5 to 6 days to reach the
lumen of the uterus.
 Parts: lined with mucosa (simple ciliated columnar ep),
muscularis, serosa
 Infundibulum
 Ampulla
 Isthmus
 Interstitial segment

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Uterine (Menstrual) Cycle and
Menstruation
 The menstrual phase occurs approximately during days 1–5
of the cycle. This phase is marked by sloughing of the functional
layer and lasts through the period of menstrual bleeding.
 The proliferative phase follows, spanning approximately
days 6–14. The initial development of the functional layer of the
endometrium overlaps the time of follicle growth and estrogen
secretion.
 The last phase is the secretory phase, which occurs at
approximately days 15–28. During the secretary phase,
increased progesterone secretion from the corpus luteum
results in increased vascularization and development of uterine
glands.
 If the oocyte is not fertilized, the corpus luteum degenerates,
and the progesterone level drops dramatically.
 Without progesterone, the functional layer lining sloughs off, and
the next menstrual phase begins.

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Menstrual cycles

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Vagina
 The vagina is
 thick-walled, fibromuscular tube
 forms the inferior-most region of the female reproductive tract
 measures about 10 centimeters in length in an adult female.
 The vagina connects the uterus with the outside of the body
anteroventrally
 functions as the birth canal.
 Also the copulatory organ of the female
 Serves as the passageway for menstruation.
 The vaginal wall is heavily invested with both blood vessels and
lymphatic vessels.
 The vagina’s relatively thin, distensible wall consists of three
tunics:
 an inner mucosa, a middle muscularis, and an outer adventitia

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External Genitalia
 The external sex organs of the female, are collectively called the
vulva.
 The mons pubis is an expanse of skin and subcutaneous
connective tissue immediately anterior to the pubic symphysis.
 covered with pubic hair in postpubescent females
 labia majora
 labia minora

Contain the vestibule

Urethral orifice

Vaginal orifice
 Clitoris located at the anterior regions of the
labia minora
 glans
 prepuce−an external fold of the labia minora that
forms a hoodlike covering over the clitoris.

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Development
 The reproductive organs are developed from the
intermediate mesoderm. The permanent organs
of the adult are preceded by a set of structures
which are purely embryonic, and which with the
exception of the ducts disappear almost entirely
before the end of fetal life. These embryonic
structures are the Wolffian and Müllerian ducts,
also known as mesonephric and
paramesonephric ducts, respectively. The
Wolffian duct remains as the duct in males, and
the Müllerian as that of the female.

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Development of male gonads
From indifferent primordia develops
seminiferous tubules, which connects to the
mesonephros and its duct to form semen
transporting pathways. The mesonephric
duct eventually transforms into the ductus
deferens while the paramesonephric duct
disappear.

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Development of female gonads
 The primordia tissue differentiates into
the cortex and medulla. Each ovary
contains approximately 1 million of
primordial cells. Each oogonium
surrounded by a single layer of
epithelial cells forms a primary follicle.

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Descent of the gonads
 The gonadal primordia appear at the
level of L4-L5. However, neither ovaries
nor testes remain at the place of origin
but descend caudally.
 By the 3rd
month of development, the
testis reaches the pelvic cavity and by
the 7th
month – the deep inguinal ring.

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Homologous structures

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Congenital anomalies:
 Epispadias: Urethral opening on
the dorsum of the penis.
 Hypospadias: Urethra opens on
the ventral aspect of the penis or
scrotum.
 Exstrophy of bladder with
epispadias.
 Micropenis.
 Bifid penis & double penis:
Occurs if the genital tubercle splits.
EpispadiassHypospadias
Hypospadias Exstrophy & Epispadias

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Thank you for attention!