Biology 221
Anatomy & Physiology II
TOPIC 12
Reproductive System
Chapter 28
pp. 1071-1107
E. Lathrop-Davis / E. Gorski / S. Kabrhel
1
Male Anatomy Overview
The male reproductive system consists of:
• Testes
• Ducts
– epididymus
– ductus (vas) deferens
– ejaculatory duct
– urethra
• Penis
• Accessory glands
– seminal vesicles
– prostate
– bulblurethral (Cowper’s)
http://www.msms.doe.k12.ms.us/biology/anato
my/reproductive/376a.gif
Fig. 28.1, p. 1071
2
Male: Testis
• The testes are located in the scrotum.
– This is for temperature regulation and keeps
them at about 33oC; sperm die quickly at
higher temperature.
• The structure of testis includes:
– seminiferous tubules;
– interstitial cells (cells of Leydig); and
– rete testis.
Fig. 28.3, p. 1073
3
Male: Testis –
Seminiferous Tubules
• The seminiferious tubules produce sperm.
• Sustentacular (Sertoli) cells support
spermatocytes (intermediate cells) and
spermatozoa, and produce inhibin, a hormone
that inhibits FSH and LH secretion by the
anterior pituitary (adenohypophysis).
http://www.usc.edu/hsc/dental/ghisto/rep/d_74.html
http://www.usc.edu/hsc/dental/ghisto/rep/d_74.html
4
Male: Testis –
Interstitial Cells and Rete Testis
• Interstitial cells are found between the
seminiferous tubules.
– These cells produce testosterone, the main
male hormone. It promotes sperm formation
and the development and maintenance of the
male reproductive system.
• Rete testis is the first collection area after
sperm leave the seminiferous tubules.
– It consists of a network of tubules on
posterior side that lead to the epididymus.
http://www.usc.edu/hsc/dental/ghisto/rep/d_74.html
http://www.usc.edu/hsc/dental/ghisto/rep/d_75.html
Fig. 28.3, p. 1073
5
Male: Testis Coverings
• The tunica vaginalis (TV) is the outer connective
tissue and is derived from peritoneum.
• The tunica albuginea (TA) is the inner fibrous
capsule.
• Septa (S; singular = septum) are extensions of
the tunica albuginea that divide the testis into
sections.
Fig. 28.3, p. 1073
http://www.usc.edu/hsc/dental/ghisto/rep/d_72.html
6
Male: Duct System
• The epididymis is the site of sperm maturation
and storage.
• The ductus (vas) deferens carries sperm away
from the testis to the ejaculatory duct.
• The ejaculatory duct extends from where the
ducts from the seminal vesicles join the ductus
(vas) deferens to the urethra within the prostate
gland.
Fig. 28.1, p. 1071
http://www.msms.doe.k12.ms.us/biology/anatomy/reproductive/376a.gif
7
Male: Urethra
• The prostatic urethra runs through the prostate
gland from the urinary bladder.
• The membranous urethra runs from the prostate
to the penis. It is the shortest segment of the
urethra.
• The penile urethra runs through penis and is
surrounded by erectile tissue.
Fig. 28.4, p. 1075
http://www.nku.edu/~dempseyd/REPRODUCTION_2.htm
8
Male: Penis
• The penis is designed to deliver sperm into vagina
of female.
• The penis contains tissues that aid delivery by
filling with blood during erection.
– The corpora cavernosa are paired structures
on the superior side of the penis.
– The corpus spongiosum surrounds the urethra
on the inferior side of the penis.
Fig. 28.4, p. 1075
http://wbiomed.curtin.edu.ou/teach/humanbiol/hb134/134hist/penis.htm
9
Male Accessory Glands & Semen
• Semen consists of sperm plus products of the
accessory glands that support and nourish the
sperm.
• Glands include the:
– Seminal vesicles (SV)
– Prostate gland
– Bulbourethral (Cowper’s) glands
Fig. 28.1, p. 1071
10
Male Accessory Glands:
Seminal Vesicles
• The seminal vesicles produce about 60% of all
semen.
• The alkaline fluid neutralizes the acidity of the
male urethra and female vagina.
• Fructose included in the fluid nourishes the
sperm.
Fig. 28.1, p. 1071
11
Male Accessory Glands: Prostate
• The prostate gland encircles the urethra below
the bladder (hence the name “prostate urethra”).
• The prostate produces about 30% of the semen.
• The products play a role in activating and
protecting sperm.
– Citrate nourishes sperm.
http://www.usc.edu/hsc/dental/ghisto/rep/d_96.html
Fig. 28.1, p. 1071
12
Male Accessory Gland:
Bulbourethral Glands
• The paired bulbourethral glands lie near the base
of the penis.
• The bulbourethral glands produce mucus that
neutralizes acidity of traces of urine in the male
urethra.
Fig. 28.1, p. 1071
13
Male Reproductive Physiology:
Sperm Production Overview
• Sperm (and ova) are produce by meiotic cell
division.
• Sperm production involves two stages:
– Spermatogenesis is the process by which
diploid spermatocytes divide by meiotic cell
division to yield haploid gametes called
spermatids.
– Spermiogenesis is the process of maturation of
spermatids into functional spermatozoa
(sperm).
14
Comparison of Mitosis & Meiosis
Mitosis
Meiosis
Single division
2 divisions
1. Meiosis I reduces number
of chromosomes by half
2. Meiosis II separates
chromatids into 4 separate
haploid cells
Produces 2 genetically
identical diploid daughter
cells
Produces 4 genetically
distinct haploid daughter cells
Fig. 28.6, p. 1078
15
Male: Spermiogenesis
Spermiogenesis involves the development of:
• a flagellum (whip-like “tail”) for movement;
• an acrosome that contains digestive enzymes for
egg penetration; and
• a midpiece that has lots of mitochondria to
provide ATP (energy) for movement.
Fig. 28.9, p. 1082
18
Male: Sustentacular Cells
• Sustentacular cells are also called Sertoli cells.
• They surround and support the developing
spermatocytes and spermatids.
• Sustentacular cells extend from the basal lamina
of the seminiferous tubule to the lumen of
tubule.
Fig. 28.8, p. 1081
19
Male: Sustentacular Cells
Sustentacular cells form the blood-testis barrier.
• Their cells are joined by tight junctions, which
prevents contact between developing sperm and
blood.
– This is important because sperm are first
produced after the immune system has
developed its sense of “self” .
– Sperm would be recognized as foreign if
contacted blood.
• These cells produce fluid different from the
surrounding interstitial fluid (higher in androgens,
amino acids, potassium).
20
Male: Hormonal Regulation of Function
Hypothalamus secretes GnRH
(Gonadotropin-releasing hormone)

GnRF stimulates the adenohypophysis to release
FSH
and
LH


• FSH indirectly stimulates
LH stimulates
testosterone secretion
testosterone
• stimulates spermatogenesis
secretion
• stimulates inhibin secretion
Fig. 28.10, p. 1085
(inhibits FSH and LH production)
http://www.uronet.org/visual/nov99/3.htm
21
Male: Testosterone
Testosterone stimulates:
• spermatogenesis (production of sperm);
• development and maintenance of male secondary
sex characteristics (e.g., facial hair, large
muscles, etc.) and male reproductive organs;
• development of the sexual drive in the CNS;
• protein synthesis in muscle cells and growth of
muscle and bone;
http://www.uronet.org/visual/nov99/1.htm
Fig. 28.10, p. 1085
22
Female Anatomy Overview
The female reproductive system consists of:
• Ovaries
• Fallopian (uterine) tubes (oviducts)
• Uterus
• Vagina
• Mammary glands
• Supporting structures
http://www.med.umich.edu/lrc/coursepages/M1/anatomy/html/radiology
/pelvis/hysterosalpingogram.html
Fig. 28.11, p. 1086
24
Female: Ovaries
• The ovaries are located in the pelvic cavity lateral
to the uterus.
• Ligaments anchor the ovary to other structures.
– The ovarian ligament anchors ovary to uterus.
– The broad ligament consists of parietal
peritoneal tissue
° The suspensory ligament anchors the ovary
to the lateral pelvic wall
° The mesovarium holds the ovary between the
ovarian and suspensory ligaments.
Fig. 28.14, p. 1089
25
Female: Ovaries
• The ovary contains oocytes surrounded by
follicles.
• The ovary releases secondary oocytes into the
pelvic cavity.
Fig. 28.14, p. 1089
26
Female: Uterine (Fallopian) Tubes
• The fallopian tube carries the oocyte toward the
uterus.
• Fimbriae are fingerlike extensions of the ends of
the fallopian tubes.
– The fimbriae immediately pick up the secondary
oocyte released from the ovary and transfer it
into the fallopian tube.
• Smooth muscle and cilia on the simple columnar
epithelium help move the oocyte toward the
uterus.
http://www.med.umich.edu/lrc/coursepages/M1/anatomy/html/ra
diology/pelvis/hysterosalpingogram.html
Fig. 28.14, p. 1089
27
Female: Uterus
• The uterus is the normal site of implantation of
the fertilized ovum and development of the fetus.
• The uterus wall has 3 layers:
– The endometrium is the inner layer.
– The myometrium is the middle layer of smooth
muscle.
– The perimetrium is the outer covering of
visceral peritoneum.
Fig. 28.14, p. 1089
28
Female: Uterus – Endometrium
• The endometrium consists of two sublayers:
– the stratum functionalis is the sublayer
closest to the lumen; it undergoes cyclical
changes every month;
– the stratum basalis lines the myometrium and
forms a new stratum functionalis each month.
• The endometrium forms the maternal part of
the placenta.
http://www.usc.edu/hsc/dental/ghisto/rep/d_33.html
http://www.usc.edu/hsc/dental/ghisto/rep/d_34.html
29
Female:
Myometrium & Perimetrium
• The myometrium consists of smooth muscle.
– contracts under hormonal and parasympathetic
control to expel sloughed off endometrial
tissue each or the fetus at the end of
pregnancy.
• The perimetrium (also called the serosa) is the
peritoneal covering.
Fig. 28.14, p. 1089
30
Female: Cervix and Vagina
• The cervix is the narrow “neck” of the uterus.
• The vagina, also called the “birth canal”, is lined
with stratified squamous epithelium because it is
subject to abrasion.
Fig. 28.14, p. 1089
31
Mammary Glands
• The mammary glands are modified sweat glands.
• They are only functional in females.
• The mammary glands produce milk to nourish the
newborn.
• Mile is produced and released under hormonal
control.
– Prolactin stimulates milk production in
lactating females.
– Oxytocin stimulates milk ejection when the
infant suckles.
Fig. 28.17, p. 1093
32
Female: Ovarian Cycle Overview
• The ovarian cycle consists of two phases:
Follicular (1-6 in diagram) & Luteal (7-9 in
diagram)
Fig. 28.20, p. 1097
33
Follicular Phase – 1st to 14th Day
• Each month, several primordial follicles develop
into primary follicles.
• Usually only one primary follicle develops into a
secondary follicle.
– The zona pellucida forms as a thick, transparent
membrane around the oocyte.
– The primary follicle begins to produce
estrogens.
– The antrum, an opening around the oocyte,
forms and the primary follicle becomes a
secondary follicle.
Fig. 28.12, p. 1087
Fig. 28.19, p. 1095
34
Follicular Phase – 1st to 14th Day
• The follicle is called a secondary follicle when
antrum is present.
• The secondary follicle enlarges and becomes a
vesicular (Graafian) follicle.
– The corona radiata forms and surrounds the
oocyte.
– The primary oocyte divides (finishes meiosis I)
to form 1 secondary oocyte and 1 polar body.
Fig. 28.12, p. 1087
Fig. 28.19, p. 1095
35
Ovulation and Luteal Phase
– 14th to 28th day
• Ovulation refers to the release of the secondary
oocyte from the ovary.
– The ovary is arrested in metaphase of meiosis
II.
• The Luteal Phase occurs from the 14th to 28th day.
– Cells of ruptured Graafian follicle become the
corpus luteum, which begins to secrete
progesterone and continues to secrete
estrogen.
– The corpus luteum degenerates in about 10
days if pregnancy does not occur to become the
corpus albicans.
Fig. 28.12, p. 1087
36
Ovarian Cycle: Hormonal Control
• The hypothalamus secretes GnRH (gonadotropin
releasing hormone).
• GnRH stimulates release of FSH (follicle
stimulating hormone) and LH (lutenizing hormone)
from the anterior pituitary.
– FSH (& LH) stimulate follicle growth.
Fig. 28.21, p. 1098
37
Ovarian Cycle: Hormonal Control
• The enlarged follicles begin to secrete
estrogens.
• Rising estrogen levels initially inhibit release of
FSH & LH from anterior pituitary, but also
stimulate it to produce and accumulate these
hormones (i.e., accumulate FSH and LH).
Fig. 28.21, p. 1098
38
Ovarian Cycle: Hormonal Control
• Once estrogen levels reach critical level, it exerts
positive feedback on the hypothalamus &
pituitary.
– The result is a sudden surge of LH.
• The surge of LH results in:
– completion of meiosis I; and
– release of the secondary oocyte from the
Graafian follicle (i.e., ovulation).
° Ovulation results from positive feedback
influence of estrogen on secretion of LH
Fig. 28.21, p. 1098
39
Ovarian Cycle: Hormonal Control
• The surge of LH causes the ruptured follicle to
become the corpus luteum and stimulates
production of estrogens and progestins from it.
• Increased progesterone and estrogen cause a
decline in LH.
– With the decline in LH, the corpus luteum is
less stimulated and eventually becomes the
corpus albicans.
Fig. 28.21, p. 1098
40
Uterine (Menstrual) Cycle
• The menstrual cycle refers to the cyclical
changes in the endometrium that prepare it for
implantation of a fertilized ovum.
• There are three phases to the mentrual cycle:
– the menstrual phase,
– the proliferative phase, and
– the secretory phase.
Fig. 28.15, p. 1091
Fig. 28.22, p. 1100
41
Menstrual Phase (Days 1-5)
• During the menstrual phase, the stratum
functionalis is shed and passes through vagina as
menstrual flow.
• This is a response to declining estrogen levels.
http://lpc1.clpccd.cc.ca.us/lpc/zingg/anat/alecture/ach27f/sld021.htm
42
Proliferative Phase (Days 6-14)
• During the proliferative phase, the stratum
functionalis is rebuilt by the stratum basale in
response to stimulation from ovarian estrogens.
• The endometrial glands become larger.
• Estrogen induces formation of additional
progesterone receptors on the uterus.
• The blood supply for the endometrium increased.
43
Secretory Phase (Days 15-28)
• During the secretory phase, the endometrium
continues to develop in response to ovarian
progesterone.
• The endometrial glands begin to secrete nutrient
substances.
• Toward the end, the decline in progesterone
caused by the declining activity of the corpus
luteum results in declining condition of the blood
vessels in the stratum functionalis.
– Eventually this results in its loss and the start
of next menstrual phase.
44
Correlation of Hormones With
Cycles
• During the menstrual phase, all hormones are at
their lowest levels
• During the proliferative phase, estrogens
secreted by ovary cause proliferation of
endrometrial cells such that stratum functionalis
is rebuilt from the stratum basale.
Fig. 28.22
45
Correlation of Hormones With
Cycles
• During the secretory phase,
– high levels of progesterone continue to
stimulate the development of the stratum
functionalis; and
– levels of estrogen decrease somewhat
Fig. 28.22
46
Disorders of Reproduction: STDs
• Gonorrhea is an infection by Neisseria
gonnorrhoeae bacteria.
– It causes inflammation of the urethra and can
lead to pelvic inflammatory disease in females.
• Syphilis is an infection by Treponema pallidum
bacteria. Syphilis damages the internal organs.
Late stage symptoms include loss of motor
coordination, paralysis, numbness, and gradual
blindness and dementia.
• Chlamydia is an infection by Chlamydia bacteria;
causes pelvic inflammatory disease, urethritis,
among other things
47
Disorders of Reproduction: STDs
• Genital warts is an infection by the human
papillomavirus (HPV).
– This virus causes warts in the genital area
– The virus also increases the probability of
developing cervical or penile cancer.
• Genital herpes is an infection by the herpes
simplex virus
– Genital herpes causes lesions on the genital
area.
– It is treated with acyclovir, an antiviral drug.
48
Other Disorders of Reproduction
• Pelvic inflammatory disease (PID) is a severe
inflammation of the lower peritoneal cavity
generally caused by STDs.
• Ectopic pregnancy refers to the implantation of
an embryo outside the uterus (e.g., in oviduct or
pelvic cavity).
49
Other Disorders of Reproduction
• Hypertrophy of prostate is an enlargement of the
prostate gland.
– This impinges on prostate urethra making
urination difficult and increasing the likelihood
of bladder infection
– Hypertrophy is common in elderly males.
• Breast cancer is cancer of the mammary gland.
– It strikes 1:8 women.
50
Important Developmental
Milestones
• 8 weeks
– ossification begins
– blood cells begin to be formed by liver
– all systems present (at least as basic plan)
• 9-12 weeks
– bone marrow begins to form blood cells
• 26 weeks
– surfactant production begins in lung
• 38-42 weeks
– birth
° if less than 38 weeks, systems not as developed
° if more than 42 weeks, placenta starts to degrade
• Milestones will be covered with Topic 13, Development.
51