Endocrinology of reproduction
Reproductive System
28-1
Anatomy of Male
Reproductive System
• Testes
• Series of ducts
– Epididymides
– Ductus deferentia
– Urethra
• Accessory glands
– Seminal vesicles
– Prostate gland
– Bulbourethral glands
• Supporting structures
– Scrotum
• 2 chambered sac that
contains testes
• Dartos and cremaster
muscles help regulate
temperature
– Penis
• Perineum
– Diamond-shaped areas
between thighs
28-2
Male Pelvis
28-3
Testes
• Glands
– Exocrine
– Endocrine
• Compartments divided
by septa
– Seminiferous tubules
• Empty into rete testis
• Empties into efferent
ductules
– Interstitial or Leydig
cells
• Descent
– Pass from abdominal
cavity through inguinal
canal to scrotum
• Cryptorchidism
– Failure of of one or
both of testes to
descend into scrotum
– Prevents normal sperm
development
28-4
Histology of Testis
28-5
Descent of Testes
28-6
Sperm Cell Development
• Spermatozoa produced
in seminiferous tubules
• Spermatogonia divide
(mitosis) to form
primary spermatocytes
• Primary spermatocytes
(first division of
meiosis) divide to form
secondary spermatocytes
• Secondary spermatocytes
(second division of
meiosis) divide to form
spermatids
• Spermatids develop an
acrosome and flagellum
• Sertoli cells nourish
sperm cells and form a
blood-testis barrier and
produce hormones
28-7
Spermatogenesis
28-8
Meiosis
28-9
Ducts
• Epididymis
– Site of sperm cell
maturation
• Ductus deferens or vas
deferens
– Passes from
epididymis into
abdominal cavity
• Ejaculatory duct
– Joining of ductus
deferens and seminal
vesicle
• Urethra
– Extends from urinary
bladder to distal end of
penis
– Passageway for urine
and male reproductive
fluids
– 3 parts
• Prostatic urethra
• Membranous urethra
• Spongy or penile
urethra
28-10
Male Reproductive Structures
28-11
Penis
• Three columns of
erectile tissue that
engorge with blood
– Corpora cavernosa (2)
– Corpus spongiosum (1)
• Glans penis
– Prepuce or foreskin
covers
• Circumcision: Surgical
removal
• External urethra
orifice
28-12
Penis
28-13
Accessory Glands
• Bulbourethral glands
• Seminal vesicles
– Empty into ejaculatory
duct
– Produce about 60% of
semen
• Prostate gland
– Produces about 30% of
semen
– Contribute about 5% to
semen
• Secretions
– Semen
• Composite of sperm
cells and secretions
– Emission
• Discharge of semen into
prostatic urethra
– Ejaculation
• Forceful expulsion of
semen from urethra
28-14
Regulation of Sex Hormone
Secretion
• Hypothalamus releases
– GnRH or LHRH which
stimulates
• LH or ICSH to produce
testosterone
• FSH to stimulate sperm
cell formation
• Inhibin inhibits FSH
secretion from anterior
pituitary
28-15
Puberty and Testosterone
• Puberty
– Age at which
individuals become
capable of sexual
reproduction
• Before puberty small
amounts of testosterone
inhibit GnRH release
• During puberty
testosterone does not
completely suppress
GnRH release, resulting
in increased FSH,LH,
and testosterone
• Testosterone
– Produced by interstitial
cells, adrenal cortex
and sustentacular cells
– Causes development of
male sex organs in
embryo, stimulates
descent of testes,
causes enlargement of
genitals and necessary
for sperm cell
formation
28-16
Male Sexual Behavior and
Male Sex Act
• Male sexual behavior
– Testosterone required to initiate and maintain
• Male sex act
– Complex series of reflexes that result in
erection of penis, secretion of mucus into
urethra, emission, ejaculation
– Sensations result in orgasm associated with
ejaculation and then resolution
28-17
Neural Control of Erection
• Stimulation
– Tactile or
psychological
– Parasympathetic
• Erection due to
vasodilation of blood
vessels
– Sympathetic
• Causes erection,
emission, ejaculation
• Erectile Dysfunction
28-18
Anatomy of Female
Reproductive System
• Female reproductive organs
–
–
–
–
–
–
Ovaries
Uterine tubes
Uterus
Vagina
External genital organs
Mammary glands
28-19
Female Pelvis
28-20
Uterus, Vagina, Uterine Tubes,
Ovaries and Supporting Ligaments
28-21
Ovary Histology
28-22
Maturation of Follicle and Oocyte
28-23
Maturation and Fertilization
of Oocyte
28-24
Follicle and Oocyte Development
• Oogenesis is the production
of a secondary oocyte in
ovaries
• Oogonia are cells from
which oocytes develop
• Primary oocytes are
surround by granulosa cells
and called a primordial
follicle
• Primordial follicle becomes
a primary follicle when
oocyte enlarges and cells
change
• Primary follicle becomes
secondary follicle and
enlarges to form mature or
graafian follicle
– Usually only one is ovulated,
others degenerate
• Primary oocyte completes
first meiotic division to
produce secondary oocyte
and a polar body
• Secondary oocyte begins
second meiotic division,
which stops in metaphase II
28-25
Ovulation and Follicle Fate
• Ovulation
– Follicle swells and
ruptures, secondary
oocyte is released from
ovary
– Second meiotic
division completed
when secondary oocyte
unites with sperm cell
to form zygote
• Fate of the follicle
– Graafian follicle
become corpus luteum
– If fertilization occurs,
corpus luteum persists
– If no fertilization,
becomes corpus
albicans
28-26
Uterine Tubes and Uterus
• Uterine or fallopian
tubes or oviducts
– Open directly into
peritoneal cavity to
receive oocyte from
ovary
– Transport oocyte or
zygote from ovary to
uterus
• Uterus
– Parts: Body, isthmus,
cervix
– Composed of 3 layers
• Perimetrium: Serous
membrane
• Myometrium: Smooth
muscle
• Endometrium: Mucous
membrane
28-27
Vagina and Perineum
• Perineum
• Vagina
– Female organ of
copulation
– Allows menstrual flow
and childbirth
– Hymen covers the
vaginal opening or
orifice
– Divided into two
triangles
• Urogenital: Contains
the external genitalia
• Anal triangle
• Clinical perineum
– Region between
vagina and anus
– Episiotomy: Incision to
prevent tearing during
childbirth
28-28
Female External Genitalia
• Vulva or pudendum or
external female genitalia
– Vestibule: Space
• Labia minora: Form
borders on sides
• Clitoris: Erectile
structure
– Corpora cavernosa
– Corpora spongiosa
– Labia majora
• Unite to form mons
pubis
28-29
Female Perineum
28-30
Mammary Glands
• Organs of milk
production located
within mammae or
breasts
– Consist of glandular
lobes and adipose
tissue
– Cooper’s ligaments
support the breasts
28-31
Puberty and Menstrual Cycle
• Menstrual Cycle
• Puberty
– Begins with menarche
or first episode of
menstrual bleeding
– Begins when GnRH
levels increase
– About 28 days long
– Phases
•
•
•
•
Menses
Proliferative phase
Secretory phase
Menses
– Amenorrhea: Absence
of a menstrual cycle
– Menopause: Cessation
of menstrual cycles
28-32
Menstrual Cycle
28-33
Hormone Regulation during
Menstrual Cycle
28-34
Female Sexual Behavior
and Sex Act
• Female sexual behavior
– Depends on hormones
• Androgens and steroids
– Depends on
psychological factors
• Female sex act
– Parasympathetic
stimulation
• Blood engorgement in
clitoris and around vaginal
opening
• Erect nipples
• Mucouslike fluid extruded
into vagina and through
wall
– Orgasm not necessary
for fertilization to occur
28-35
Female Fertility and Pregnancy
• Female fertility
– Sperm ejaculated into
vagina during
copulation and
transported through
cervix and uterine
tubes to ampulla
– Sperm cells undergo
capacitation
• Pregnancy
– Oocyte can be
fertilized up to 24
hours after ovulation
– Sperm cells can be
viable for up to 6 days
in female tract
– Ectopic pregnancy:
Implantation occurs
anywhere other than
uterine cavity
28-36
Sperm Cell Movement
28-37
Changes in Hormones During
Pregnancy
28-38
Control of Pregnancy
• Behavioral methods
– Abstinence
– Coitus interruptus
– Rhythm method
• Barrier methods
– Condom
• Male and female
– Diaphragm
– Cervical cap
– Spermicidal agents
• Lactation
• Chemical methods
– Oral contraceptives
– Injections as DepoProvera
– Implants
– Morning-after pills
• Surgical methods
– Vasectomy
– Tubal ligation
– Abortions
28-39
Effects of Aging
• Male
– Decrease in size and
weight of testes
– Decrease in sperm
production
– Prostate gland enlarges
and increase in cancer
– Impotence is agerelated
– Decrease in sexual
activity
• Female
– Menopause
– Decrease in size of
uterus and vaginal wall
thins
– Age related increase in
breast, uterine, ovarian
cancer
28-40