HUMAN ANATOMY
LECTURE TWENTY-ONE
REPRODUCTIVE
SYSTEM
FUNCTIONS
MALE REPRODUCTIVE FUNCTIONS
• Production of sperm cells
• Sustaining and transfer of sperm to female - nutrients, environment to mature,
and secretions of semen
• Production of male sex hormones - control male development and functioning
of male reproductive system
FEMALE REPRODUCTIVE FUNCTIONS
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Production of female sex cells
Reception of sperm cells from the male and transportation to site of fertilization
Nurturing development of and providing nourishment for fetus
Production of female sex hormones - control development of female
reproductive system and female body, reproductive behaviour
MALE ANATOMY
MALE PERINEUM
SCROTUM
• 2 chambered sac divided into right and
left halves separated by a C.T. septum
(raphe)
• Beneath epidermus is layer of loose C.T.
and smooth muscle (dartos)
• Dartos and cremasteric muscles help
regulate temperature of the testes by
raising them into the abdomen
TESTIS
• Located outside the body to keep sperm
at lower than body temperature for
development
• Serve as both exocrine - produce sperm
and endocrine - release testosterone
• Tunica Vaginalis - serous
membrane lining scrotal
cavity and reduces friction
between scrotal and testicular
surfaces
• Tunica Albuginea - thick
white C.T.
- divides testes into lobules
- within lobules are
seminiferous tubules and
interstitial (Leydig) cells
(secrete testosterone)
• Tubes carrying sperm:
- seminiferous tubules (site of
sperm production)
- tubuli recti and rete testis
(pathway to epididymis)
DESCENT OF THE TESTES
SPERM CELL DEVELOPMENT
Spermatozoa are produced in seminiferous tubules at puberty. GnRH secretion
increased leading to increased LH and FSH release. FSH promotes sperm
production and also promotes interstitial cells to produce large amounts of
testosterone.
• Spermatogonia divide (mitosis) forming primary spermatocytes
• Primary spermatocytes divide (1st division of mitosis) forming secondary
spermatocytes
• Secondary spermatocytes divide (2nd division of mitosis) forming
spermatids
• Spermatids develop an acrosome and flagellum
• Sustentacular (Sertoli or nurse) cells nourish sperm cells, form a bloodtestis barrier and produce hormones
- attached to sperm during development
• Sperm move to epididymis to mature
MALE DUCTS (not ducks)
EFFERENT DUCTULES - lead out of testis, rete empty into
EPIDIDYMIS - site of sperm cell maturation
- long coiled tubules on surface of teste
- have stereocilia in pseudostratified columnal epithelium increasing
surface area to facilitate absorption of fluid from lumen of the duct
- smooth muscle moves sperm through
DUCTUS DEFRENS - from epididymis into abdominal cavity
- associated with blood vessels, lymphatic vessels, and nerves supplying testis
all form spermatic cord (surrounded by cremaster muscle and C.T. sheath)
- extends into abdominal wall through inguinal canal - just before reaching
prostate gland diameter increases to become ampulla of ductus deferens
- smooth muscle wall that propels sperm cells by peristalsis
EJACULATORY DUCT - joins ductus deferens and seminal vesicle
- extends into prostate gland and joins urethra within prostate
ACCESSORY GLANDS
SEMINAL VESICLES - saclike glands near ampulla of ductus deferens
• Empty into ejaculatory duct
• Produce 60% of semen
• Secretion contains: fructose, prostaglandins (stimulates muscle contractions in
both male and female), fibrinogen (forms clot in vagina for protection)
• Secretion are alkaline to neutralize acids of vagina
• Activate flagella in previously inactive sperm cells
PROSTATE GLAND - muscular gland surrounding urethra and the two
ejaculatory ducts
• Produces 30% of semen
• Thin, milky secretion high pH containing seminalplasmin (antibiotic
preventing urinary tract infection in males)
BULBOURETHRAL GLANDS - at base of penis
• Ducts empty into urethral lumen
• Have compound tubuloalveolar mucous glands that secrete thick alkaline
mucus to lubricate glans of penis and neutralize any urinary acids
URETHRA
• Extends from urinary bladder to
distal end of penis
• Passageway for urine and semen
• Divided into three parts:
- prostatic region which passes
through the prostate
- membranous region which passes
through the floor of the pelvis and
is surrounded by external urinary
sphincter
- spongy (penile) region extending
the length of the penis
• Parasympathetic reflex prevents
urine from passing from urinary
bladder while semen is exiting
PENIS
• Functions for urination, semen
transport
EXTERNAL ANATOMY
• Overlying skin resembles scrotum
with layer of smooth muscle under
dermis continuous with the dartos
muscle of scrotum
• Crus and bulb = root of penis –
fixed to body wall
• Shaft (body) - moveable portion
• Glans of penis - enlargement of
corpus spongiosum
• Prepuce or foreskin covers glans
(circumcision - surgical removal)
• External urethral orifice
INTERNAL ANATOMY
• Erectile tissue is a maze of vascular channels incompletely separated by elastic
C.T. and smooth muscle - during rest arteriole branches are constricted and
muscular partitions tense to prevent blood flow in
- when nitric acid is released at synapses smooth muscles relax , arterioles
dilate and blood flows in = erection
• Three columns of erectile tissue:
- corpora cavernosa (2) expands at base to form crura
- each surrounds a central artery
- corpus spongoisum (1) surrounds spongy urethra forms the bulb of penis
- expands to form the glans
- contains many elastic fibers and a pair of small arteries
FEMALE ANATOMY
• Internal organs found within the
pelvis, between urinary bladder and
rectum
• Broad ligament attaches to both
sides of the uterus and spreads
out attaching fallopian tubes and
ovaries
OVARIES
• Function to produce immature
oocytes, secretion of female
hormones
• Outermost covering is the
ovarian epithelium (visceral
peritonium)
• Dense fibrous C.T. layer (tunica
albuginea) lies under epithelium
• The ovary is divided into:
- cortex is the outer, dense
region containing follicles with
oocytes
- medulla is the inner, looser
region containing blood vessels,
nerves, lymphatic vessels
- stroma is the C.T. that divides the
ovary
• Ovaries are held in the
pelvic cavity by ligaments
- suspensory ligament extends
from ovary to body wall
- ovarian ligament attaches ovary
to uterus, blood vessels and
nerves enter ovary through here
- mesovarium is a peritoneal fold
attaches ovary to posterior surface
of broad ligament
MATURATION OF OOCYTE
• Oogenesis - production of a
secondary oocyte in ovary
beginning before birth
• Oogonia - cells that divide by
meiosis producing primary oocytes
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5 million oocytes are produced by the 4th
month of pregnancy - about 2 million begin
dividing but stop in prophase until puberty
• Primary oocytes are surrounded by
granulosa cells and called a
primordial follicle (only 400 will reach
final stages of development)
• Primordial follicle becomes a
primary follicle when oocyte and
granulosa cells enlarge
• Primary follicle becomes secondary
follicle and enlarges to form a
Graafian follicle (matures) - only one
matures each month, others degenerate
OVULATION AND FERTILIZATION
• Ovulation - release of a secondary
oocyte from the ovary
- blood, follicular fluid and oocyte
are all released out of
ruptured follicle
• Graafian follicle becomes the
corpus luteum
• Secondary oocyte completes meiosis
after fertilization occurs
• Fertilized egg is now a zygote
• If no fertilization - corpus luteum
becomes corpus albicans (a knot of
pale scar tissue)
• If fertilization - corpus luteum
persists producing progesterone
until placenta forms
UTERINE (FALLOPIAN) TUBES
• Extend from ovary, opening directly into peritoneal cavity, to uterus
• Fimbriae - thin, finger-like processes that extend from infundibulum (funnel)
• Inner surfaces lined with cilia that beat toward the ampulla (middle segment of
tube where fertization occurs)
• Isthmus - short, narrow segment connected to uterus
• Mesosalpinx - area of broad ligament associated with uterine tube
• Three layers: outer serosa, middle smooth muscle layer, inner mucosa
- mucosa is simple ciliated columnar
epithelium with longitudinal folds
- provide nutrients for oocyte
or embryo
- cilia move fluid and
oocyte/embryo toward
uterus
UTERUS
• Provides protection, nutrition, waste removal for developing embryo
• Pear-shaped organ bent anteriorly near the base covering the anterior and
superior surfaces of the urinary bladder
• Composed of: fundus (superior region), body (main region), and cervix
(narrow, inferior area)
• Three layers:
perimetrium - outer serous membrane
myometrium - thick, smooth muscle
endometrium - mucous membrane
- simple columnar epithelial cells with simple tubular glands
- functional layer that is sloughed off during menstruation
• Cervix - more rigid and less contractile than the rest
• Cervical canal - lined with mucous glands, mucus plug near ovulation forms
when consistency of secretion changes to seromucus
VAGINA
• Extends from uterus (cervix) to
outside
• Receives penis during intercourse,
allows menstrual flow and childbirth
• Hymen (thin mucous membrane)
covers vaginal opening - several
holes allows menstrual flow
• Outer smooth muscle layer with
many elastic fibers allow stretching
during intercourse and child birth also longitudinal folds and rugae
• Inner mucous membrane lining of
moist stratified squamous
epithelium forms protective layer
• Fornix - superior domed portion
attached to sides of cervix
EXTERNAL GENITALIA
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Vulva or pudendum - external area
including vestibule and external genitalia
Vestibule - space where vagina and urethra
open
Labia minora - thin, longitudinal skin
folds bordering the vestibule
Clitoris - small erectile structure in
anterior of vestibule, has fold of skin
covering called prepuce
On either side of vestibule there are
openings to the greater vestibular glands
- maintain moistness
Vaginal orifice - contains erectile tissue
Labia majora - prominent rounded folds
of skin on either side of labia minora,
conceal contents of vulva
- meet anteriorly to form elevated tissue mons pubis over the symphsis pubis
- medial surfaces covered with
sebaceous and sweat glands
PERINEUM
MENSTRUAL CYCLE
At puberty
• Begins with menarche (first
episode of menstrual bleeding)
• Begins when GnRH levels increase
Menstrual Cycle
• About 28 days long
• Phases:
- menses
- proliferative or follicular phase
(follicle matures)
- secretory phase (maturation and
secretion of uterine glands,
presence of corpus luteum)
• Amenorrhea - absence of menstrual
cycle
• Menopause - cessation of menstrual
cycles