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CHAPTER
27
The Reproductive System
Objectives
Anatomy of the Male Reproductive System
1. Describe the structure and function of the testes, and explain the importance of their
location in the scrotum.
Physiology of the Male Reproductive System
4. Describe the phases of the male sexual response.
5. Define meiosis. Compare and contrast it to mitosis.
Anatomy of the Female Reproductive System
8. Describe the location, structure, and function of the ovaries.
Physiology of the Female Reproductive System
12. Describe the process of oogenesis and compare it to spermatogenesis.
13. Describe ovarian cycle phases, and relate them to events of oogenesis.
Sexually Transmitted Infections
17. Indicate the infectious agents and modes of transmission of gonorrhea, syphilis,
Developmental Aspects of the Reproductive System
18. Discuss the determination of genetic sex and prenatal development of male and female
structures.
Suggested Lecture Outline
I. Anatomy of the Male Reproductive System (pp. 1019–1026; Figs. 27.1–27.5)
A. The scrotum is a sac of skin and superficial fascia that hangs outside the abdominopelvic
cavity at the root of the penis and houses the testes (pp. 1019–1020; Figs. 27.1–27.4).
1. Since viable sperm cannot be produced at body temperature, the scrotum provides an
environment 3° below the core body temperature.
B. The testes are the primary reproductive organ of the male, producing both sperm and
testosterone (pp. 1020–1022; Figs. 27.1–27.2).
1. Each testis is surrounded by two tunics: the outer tunica vaginalis, derived from the
peritoneum, and the inner tunica albuginea, which serves as the fibrous capsule
surrounding the testis.
2. The testes are divided into lobules containing one to four seminiferous tubules, where
sperm are produced.
5. Seminiferous tubules in each lobule converge into a straight tubule that conveys sperm
into the rete testis.
6. From the rete testis, sperm pass through efferent ductules into the epididymis, which
stores them until ejaculation.
9. A spermatic cord containing autonomic nerve fibers, blood vessels, and lymphatics
passes through the inguinal canal to each testis.
C. The male perineum is a diamond-shaped region that extends from the pubic symphysis
to the coccyx from front to back and between the ischial tuberosities from side to side; it
suspends the scrotum and contains the root of the penis and the anus (p. 1022, Fig. 27.4).
D. The penis is the copulatory organ, designed to deliver sperm into the female reproductive
tract (pp. 1022–1023; Figs. 27.1–27.2, 27.5).
1. The penis is made of an attached root and a free body that ends in an enlarged tip, the
glans penis.
E. The Male Duct System (p. 1024; Figs. 27.1, 27.5)
1. The epididymis consists of a highly coiled tube that provides a place for immature
sperm to mature and to be expelled during ejaculation.
a. Immature sperm from the testis are moved slowly through the epididymis through
fluids containing antimicrobial proteins and defensins.
b. Sperm gain the ability to swim within the epididymis.
F. Male Accessory Glands (pp. 1024–1026; Figs. 27.1, 27.5)
1. The seminal glands lie on the posterior bladder wall; their alkaline secretion accounts
for 70% of the volume of semen consisting of fructose, ascorbic acid, a coagulating
enzyme (vesiculase), and prostaglandins.
G. Semen is a milky white, somewhat sticky mixture of sperm and accessory gland
secretions that provides a transport medium for sperm, as well as performing supportive
and protective roles for sperm within the female reproductive tract (p. 1026).
II. Physiology of the Male Reproductive System (pp. 1026–1035; Figs. 27.6–27.11;
Table 27.1)
A. Male Sexual Response (pp. 1026–1027)
1. Erection, enlargement, and stiffening of the penis result from the engorgement of the
erectile tissues with blood triggered during sexual excitement.
2. Ejaculation is the propulsion of semen from the male duct system triggered by the
sympathetic nervous system.
B. Spermatogenesis is the series of events in the seminiferous tubules that produce male
gametes (sperm or spermatozoa) (pp. 1027–1033; Figs. 27.6–27.9).
1. Most body cells contain 23 homologous pairs of chromosomes—one member of each
pair originates from each parent—resulting in a diploid chromosome complement, 2n.
2. Gametes are haploid cells, n, that contain only one member of each homologous
chromosome, for a total of 23 chromosomes per cell.
3. Gamete formation in males and females involves meiosis, a process involving two
consecutive nuclear divisions following only one round of DNA replication that result
in the production of four haploid daughter cells.
4. Spermatogenesis: Summary of Events in the Seminiferous Tubules
a. Spermatogenesis begins during puberty when the spermatogonia divide to produce
type A daughter cells that maintain the stem cell line and type B daughter cells that
get pushed toward the lumen to become primary spermatocytes and ultimately
sperm.
C. Hormonal Regulation of Male Reproductive Function (pp. 1033–1035; Figs. 27.10–
27.11; Table 27.1)
1. The hypothalamic-pituitary-gonadal axis refers to the relationship between the
structures that regulate the production of gametes and sex hormones.
a. The hypothalamus releases gonadotropin-releasing hormone (GnRH), which
controls the release of the anterior pituitary hormones follicle-stimulating hormone
2. Mechanism and Effects of Testosterone Activity
a. Testosterone is synthesized from cholesterol and exerts its effects by activating
specific genes, causing specific proteins to be synthesized.
III. Anatomy of the Female Reproductive System (pp. 1035–1043, Figs. 27.12–
27.18)
A. The ovaries are the primary reproductive organs of the female (pp. 1035–1036;
Figs. 27.12–27.14).
1. The ovaries produce the female gametes (ova, or eggs) and the sex hormones
(estrogens and progesterone).
2. The paired ovaries are found on either side of the uterus and are held in place by
several ligaments: the ovarian ligament anchors it medially, the suspensory ligament
anchors it laterally, and the mesovarium suspends it in between.
B. The Female Duct System (pp. 1037–1041; Figs. 27.12, 27.14–27.16)
1. The uterine tubes, or fallopian tubes or oviducts, form the beginning of the female
duct system, receive the ovulated oocyte, and provide a site for fertilization to take
2. The uterus is a hollow, thick-walled muscular organ that functions to receive, retain,
and nourish a fertilized ovum.
a. The uterus is supported by the mesometrium, the lateral cervical ligaments, the
3. The vagina provides a passageway for delivery of an infant and for menstrual blood
and also receives the penis and semen during sexual intercourse.
a. The vagina has three layers, a fibroelastic adventitia, a smooth muscle muscularis,
and an inner, ridged mucosa.
C. The external genitalia, also called the vulva or pudendum, include the mons pubis, labia,
clitoris, and structures associated with the vestibule (p. 1041; Figs. 27.12, 27.16 ).
a. The mons pubis is a fatty rounded area overlying the pubic symphysis.
D. Mammary glands are present in both sexes but usually function only in females to
produce milk to nourish a newborn baby (pp. 1041–1043; Figs. 27.17–27.18).
1. Mammary glands are modified sweat glands that are part of the integumentary system.
2. Mammary glands are contained within rounded, skin-covered breasts that lie anterior
to the pectoral muscles of the thorax.
5. Within lobes are smaller lobules, consisting of alveoli that produce milk during
lactation.
IV. Physiology of the Female Reproductive System (pp. 1043–1053; Figs. 27.19–
27.22; Table 27.1)
A. Oogenesis is the production of female gametes called oocytes, ova, or eggs (pp. 1043–
1045; Fig. 27.19).
1. A female’s total egg supply is thought to be determined at birth, although new
evidence suggests that oocytes may be produced throughout life.
2. In the fetal period the oogonia multiply rapidly by mitosis, become primordial
follicles, and then become primary follicles that begin the first meiotic division.
3. After puberty a few oocytes are activated each month by FSH, but only one will be
selected to become the dominant follicle and continue meiosis I, ultimately producing
two haploid cells: the first polar body, and a secondary oocyte.
B. The ovarian cycle is the monthly series of events associated with the maturation of the
egg (pp. 1045–1047; Fig. 27.20).
1. The follicular phase is the period of follicle growth typically lasting from days 1–14.
a. The cells surrounding the primordial follicle grow, the oocyte enlarges, developing
into a primary follicle.
2. Ovulation occurs when the ovary wall ruptures and the secondary oocyte is expelled.
3. The luteal phase, from days 14–28, is characterized by the formation of the corpus
luteum, which begins to secrete progesterone and some estrogens.
C. Hormonal Regulation of the Ovarian Cycle (pp. 1047–1049; Fig. 27.21; Table 27.1)
1. During childhood, the ovaries grow and secrete small amounts of estrogen that inhibit
2. Once the adult pattern of hormone cycles is established, the first menstrual cycle,
menarche, occurs.
3. Hormonal Interactions During the Ovarian Cycle
a. At the beginning of the cycle, rising levels of GnRH stimulate increased production
and release of FSH and LH.
b. FSH and LH stimulate follicle growth and maturation, and estrogen secretion.
D. The uterine (menstrual) cycle is a series of cyclic changes that the uterine endometrium
goes through each month in response to changing levels of ovarian hormones in the blood
and is coordinated with the phases of the ovarian cycle (pp. 1049–1051; Fig. 27.22).
1. The menstrual phase takes place on days 1–5 typically and is the time when the
endometrium is shed from the uterus; at the beginning of this stage, ovarian hormones
are at their lowest levels, and gonadotropins are beginning to rise.
2. The proliferation phase (days 6–14) is the time in which the endometrium is rebuilt.
a. As blood levels of estrogen rise, the endometrium generates a new functional layer,
3. The secretory, or postovulatory, phase (days 15–28) is the phase in which the
endometrium prepares for implantation of an embryo.
a. Spiral arteries elaborate and convert the functional layer of the endometrium to
E. Effects of Estrogens and Progesterone (p. 1051; Table 27.1)
1. Rising estrogen levels during puberty promote oogenesis and follicle growth in the
ovary, as well as growth and function of the female reproductive structures.
F. In the female sexual response, the clitoris, vaginal mucosa, and breasts become engorged
with blood, the nipples erect, and vestibular glands and the vaginal walls produce
lubricants that facilitate penis entry (pp. 1051–1053).
V. Sexually Transmitted Infections (pp. 1053–1054)
A. Gonorrhea is caused by Neisseria gonorrhoeae bacteria, which invade the mucosae of the
reproductive and urinary tracts (p. 1053).
F. Genital herpes is generally caused by the herpes simplex virus type 2, which is
transferred via infectious secretions (p. 1054).
VI. Developmental Aspects of the Reproductive System (pp. 1054–1058;
Figs. 27.23–27.24)
A. Embryological and Fetal Events (pp. 1054–1057; Figs. 27.23–27.24)
1. Sex is determined by the sex chromosomes at conception; females have two X chro-
mosomes and males have an X and a Y chromosome.
2. Sexual Differentiation of the Reproductive System
a. The gonads of both males and females begin to develop during week 5 of gestation.
3. About two months before birth the testes begin their descent toward the scrotum,
dragging their nerve supply and blood supply with them.
Cross References
Additional information on topics covered in Chapter 27 can be found in the chapters listed below.
1. Chapter 3: Cell division; tight junctions; organelles; microvilli
2. Chapter 4: Pseudostratified epithelium; tubuloalveolar glands
3. Chapter 9: Peristalsis (smooth muscle contraction)
9. Chapter 25: Male urethra
10. Chapter 28: Fertilization; vaginal environment and sperm viability; passage of sperm
through the female reproductive tract in preparation for fertilization; relationship
of spermatozoon and oocyte structure related to fertilization; uterine function in
reproduction; interruption of uterine and ovarian cycles by pregnancy; completion
of meiosis II
Lecture Hints
1. Emphasize that sperm are not capable of fertilizing an egg immediately, but must first
be naturally or artificially capacitated.
6. Be sure to indicate the reasoning behind the terms reduction and equatorial division.
Students often have difficulty with the concept of chromatid versus chromosome, and
therefore have difficulty with these terms.
7. Clearly distinguish between spermatogenesis and spermiogenesis. Students are often
confused by the similar-sounding names.
10. Emphasize that testosterone has somatic effects as well as those involving reproductive
functions.
11. Mention that the term germinal epithelium has nothing to do with ovum formation.
13. Stress that the secondary oocyte (even when initially ovulated) does not complete meio-
14. Mention that the polar bodies are actually tiny nucleate haploid cells (that are not
15. Emphasize that the events of the menstrual cycle are, in part, dependent on the hormonal
events that also control the ovarian cycle. Students make better sense out of both cycles if
they understand the interrelationship of the two.
Activities/Demonstrations
1. Audiovisual materials are listed in the Multimedia in the Classroom and Lab section of
this Instructor Guide (p. 387).
4. Project a series of images representing the process of cell reproduction to refresh stu-
dents’ memories of the sequence of events.
5. Obtain and project images of the effects of various sexually transmitted infections.
Critical Thinking/Discussion Topics
1. Discuss the need for mammograms and self-examination for early diagnosis of breast
cancer.
2. Underscore the need for self-examination for testicular cancer.
3. Describe the current treatments available for breast cancer.
Library Research Topics
1. Research the current treatments for breast cancer.
2. Investigate the current prostate disorder treatments.
3. Research the disorders associated with the menstrual cycle.
List of Figures and Tables
All of the figures in the main text are available in JPEG format, PPT, and labeled & unlabeled
format on the Instructor Resource DVD. All of the figures and tables will also be available in
Transparency Acetate format. For more information, go to www.pearsonhighered.com/educator.
Figure 27.4 The male perineum, inferior view.
Figure 27.5 Male reproductive structures.
Figure 27.6 Comparison of mitosis and meiosis in a mother cell with a diploid
number (2n) of 4.
Figure 27.12 Internal organs of the female reproductive system, midsagittal
section.
Figure 27.13 Photomicrograph of a mammalian ovary showing follicles in
different developmental phases.
Figure 27.21 Regulation of the ovarian cycle.
Figure 27.22 Correlation of anterior pituitary and ovarian hormones with
structural changes of the ovary and uterus.
Figure 27.23 Development of the internal reproductive organs.
Figure 27.24 Development of homologous structures of the external
genitalia in both sexes.
Table 27.1 Summary of Hormonal Effects of Gonadal Estrogens,
Answers to End-of-Chapter Questions
Multiple-Choice and Matching Question answers appear in Appendix H of the main text.
Short Answer Essay Questions
18. In males, the urethra transports both urine and semen and thus serves both the urinary
and reproductive systems; in females, the two systems are structurally and functionally
separate. (p. 1024)
19. The sperm regions are the head: the genetic (DNA-delivering) region; the midpiece: the
metabolizing (ATP-producing) region; and the tail: the locomotor region. (pp. 1029,
1032)
20. Oogenesis produces three tiny polar bodies, nearly devoid of cytoplasm, products of
21. The events of menopause include a decline in estrogen production, an anovulatory
ovarian cycle, and erratic menstrual periods that become shorter in length and eventually
22. Menarche is a woman’s first menstrual period, occurring when the adult pattern of
gonadotropin cycling is achieved. (p. 1047)
23. The pathway of a sperm from the male testes to the uterine tube of a female is as follows:
24. As luteinizing hormone blood levels drop, the corpus luteum begins to degenerate,
25. The vaginal epithelium houses dendritic cells that act as antigen-presenting cells in the
immune response, thus providing for early recognition of and attack against invading
26. The mucus produced by these glands cleanses the urethra of traces of urine (a potentially
disruptive presence resulting from the other function served by the “road”) before
ejaculation of semen occurs (the exciting, albeit temporary, “parade”). (p. 1026)
Critical Thinking and Clinical Application Questions
1. This patient has a prolapsed uterus, no doubt caused by the stress on the pelvic floor
muscles during her many pregnancies. Because she also has keloids, one can assume that
the central tendon to which those muscles attach has been severely damaged and many
vaginal tears have occurred. (p. 1038)
4. The man would be asked questions such as whether he has difficulty in urination or prob-
lems with impotence. The major test to be run would be to determine his sperm count.
(p. 1058)
Suggested Readings
Baczyk, D., J. Kingdom, and P. Uhlén. “Calcium Signaling in Placenta.” Cell Calcium 49 (5)
(May 2011): 350–356.
Blomberg Jensen, M., et al. “Vitamin D Is Positively Associated with Sperm Motility and
Increases Intracellular Calcium in Human Spermatozoa.” Human Reproduction 26 (6)
(June 2011): 1307–1317.
Butler, L., and N. Santoro. “The Reproductive Endocrinology of the Menopausal Transition.”
Steroids 76 (7) (June 2011): 627–635.
Christensen, Damaris. “Mammograms on Trial.” Science News 161 (17) (April 2002):
264–266.
Jegalian, Karin, and Bruce T. Lahn. “Why the Y Is So Weird.” Scientific American 284 (2)
(Feb. 2001): 56–61.
Kang-Decker, Ningling, et al. “Lack of Acrosome Formation in Hrb-Deficient Mice.”
Science 294 (5546) (Nov. 2001): 1531–1533.
Matthiesen, S. M., et al. “Stress, Distress and Outcome of Assisted Reproductive Technology
(ART): A Meta-Analysis.” Human Reproduction 26 (10) (Oct. 2011): 2763–2776.
Rodríguez-Martínez, H., et al. “Seminal Plasma Proteins: What Role Do They Play?”
American Journal of Reproductive Immunology 66 (Suppl 1) (July 2011): 11–22.
Seppa, N. “Soy Estrogens: Too Much of a Good Thing?” Science News 159 (24) (June 2001):
375.
Stewart, A. F., and E. D. Kim. “Fertility Concerns for the Aging Male.” Urology 78 (3)
(Sept. 2011): 496–499.
