1. Chapter 16 The Reproductive System Intro & Male

2. The Reproductive System
1. Gonads – primary sex organs
Testes in males
Ovaries in females
2. Gonads produce gametes (sex cells) and secrete hormones
Sperm – male
Ova (eggs) – female

3. Male Reproductive System
Accessory organs
- Seminal vesicle
- Prostate gland
- Bulbourethral gland
External genitalia
- Penis
- Scrotum
Testes
Duct system
- Epididymis
- Ductus deferens
- Urethra

4. Testes Tunica albuginea – capsule that surrounds each testis
Septa – extensions into testis; dividing it into lobules

5. Testes Each lobule contains 1-4 seminiferous tubules
Tightly coiled
Sperm-forming factories
Empty sperm into the rete testis
Sperm travels through the rete testis to epididymis
Interstitial cells produce androgens such as testosterone

6. Duct System Epididymis Comma-shaped, tightly coiled tube
Superior and along posterior lateral side
Matures and stores sperm cells (at least 20 days)
Expels sperm with the contraction of muscles in the epididymis walls to the vas deferens

7. Ductus Deferens Carries sperm from epididymis to ejaculatory duct
Passes through inguinal canal & over bladder
Moves by peristalsis
Spermatic cord – ductus deferens, blood vessels, and nerves in a connective tissue
Ends in the ejaculatory duct which unites with urethra
Vasectomy – cutting of the ductus deferens at the level of the testes to prevent transportation of sperm

9. Urethra Extends from the base of bladder to the tip of penis
Carries both urine and sperm
Sperm enters from the ejaculatory duct
Regions:
Prostatic urethra –surrounded by prostate
Membranous urethra – from prostatic urethra to penis
Spongy (penile) urethra – runs the length of the penis

10. Figure 27.4 Ureter Ampulla of ductus deferens Seminal vesicle
Urinary bladder
Ejaculatory duct
Prostate
Prostatic urethra
Orifices of prostatic ducts
Bulbourethral gland and duct
Membranous urethra
Urogenital diaphragm
Bulb of penis
Root of penis
Crus of penis
Bulbourethral duct opening
Ductus deferens
Corpora cavernosa
Epididymis
Corpus spongiosum
Shaft (body) of penis
Testis
Section of (b)
Spongy urethra
Glans penis
Prepuce (foreskin)
(a)
External urethral orifice
Dorsal vessels
and nerves
Corpora cavernosa
Urethra
Skin
Tunica albuginea of erectile bodies
Deep arteries
(b)
Corpus spongiosum
Figure 27.4

11. Accessory Glands and Semen
Seminal Vesicles
Located at the base of the bladder
Produces a thick, yellowish secretion (60% of semen)
Fructose (sugar)
Vitamin C
Prostaglandins
Substances that nourish & activate sperm

13. Figure 27.4 Ureter Ampulla of ductus deferens Seminal vesicle
Urinary bladder
Ejaculatory duct
Prostate
Prostatic urethra
Orifices of prostatic ducts
Bulbourethral gland and duct
Membranous urethra
Urogenital diaphragm
Bulb of penis
Root of penis
Crus of penis
Bulbourethral duct opening
Ductus deferens
Corpora cavernosa
Epididymis
Corpus spongiosum
Shaft (body) of penis
Testis
Section of (b)
Spongy urethra
Glans penis
Prepuce (foreskin)
(a)
External urethral orifice
Dorsal vessels
and nerves
Corpora cavernosa
Urethra
Skin
Tunica albuginea of erectile bodies
Deep arteries
(b)
Corpus spongiosum
Figure 27.4

14. Prostate Gland Encircles upper part of urethra Secretes a milky fluid
Helps activate sperm
Enters urethra through several small ducts

15. Figure 27.4 Ureter Ampulla of ductus deferens Seminal vesicle
Urinary bladder
Ejaculatory duct
Prostate
Prostatic urethra
Orifices of prostatic ducts
Bulbourethral gland and duct
Membranous urethra
Urogenital diaphragm
Bulb of penis
Root of penis
Crus of penis
Bulbourethral duct opening
Ductus deferens
Corpora cavernosa
Epididymis
Corpus spongiosum
Shaft (body) of penis
Testis
Section of (b)
Spongy urethra
Glans penis
Prepuce (foreskin)
(a)
External urethral orifice
Dorsal vessels
and nerves
Corpora cavernosa
Urethra
Skin
Tunica albuginea of erectile bodies
Deep arteries
(b)
Corpus spongiosum
Figure 27.4

16. Bulbourethral Glands Pea-sized gland inferior to prostate
Produces a thick, clear mucus
Cleanses urethra of acidic urine
Lubricant during intercourse
Secreted into penile urethra

18. Figure 27.4 Ureter Ampulla of ductus deferens Seminal vesicle
Urinary bladder
Ejaculatory duct
Prostate
Prostatic urethra
Orifices of prostatic ducts
Bulbourethral gland and duct
Membranous urethra
Urogenital diaphragm
Bulb of penis
Root of penis
Crus of penis
Bulbourethral duct opening
Ductus deferens
Corpora cavernosa
Epididymis
Corpus spongiosum
Shaft (body) of penis
Testis
Section of (b)
Spongy urethra
Glans penis
Prepuce (foreskin)
(a)
External urethral orifice
Dorsal vessels
and nerves
Corpora cavernosa
Urethra
Skin
Tunica albuginea of erectile bodies
Deep arteries
(b)
Corpus spongiosum
Figure 27.4

19. Semen Mixture of sperm & gland secretions Advantages of secretions
Fructose provides energy
Alkalinity neutralizes acidic vagina
Semen inhibits bacterial growth
Elements of semen enhance sperm motility

20. External Genitalia Scrotum - Divided sac of skin outside abdomen
- 3°C lower than body temp to protect sperm

21. External Genitalia Penis- Delivers sperm into female repro tract Shaft
Glans penis (enlarged tip)
Prepuce (foreskin)
Folded cuff of skin around proximal end
Often removed by circumcision

22. External Genitalia
3 areas of spongy erectile tissue around the urethra

23. Figure 27.4 Ureter Ampulla of ductus deferens Seminal vesicle
Urinary bladder
Ejaculatory duct
Prostate
Prostatic urethra
Orifices of prostatic ducts
Bulbourethral gland and duct
Membranous urethra
Urogenital diaphragm
Bulb of penis
Root of penis
Crus of penis
Bulbourethral duct opening
Ductus deferens
Corpora cavernosa
Epididymis
Corpus spongiosum
Shaft (body) of penis
Testis
Section of (b)
Spongy urethra
Glans penis
Prepuce (foreskin)
(a)
External urethral orifice
Dorsal vessels
and nerves
Corpora cavernosa
Urethra
Skin
Tunica albuginea of erectile bodies
Deep arteries
(b)
Corpus spongiosum
Figure 27.4

24. Figure 27.4b Male reproductive structures.
Section of (b)
Spongy urethra
Glans penis
Prepuce (foreskin)
External urethral orifice
Dorsal vessels
and nerves
Corpora cavernosa
Urethra
Skin
Tunica albuginea of
erectile bodies
Deep arteries
(b)
Corpus spongiosum

25. Spermatogenesis Production of sperm cells
Begins at puberty and continues throughout life
Occurs in the seminiferous tubules

26. Figure 27.7a Spermatogenesis.

27. Figure Comparison of mitosis and meiosis in a mother cell with a diploid number (2n) of 4 (1 of 2).
Mother cell
(before chromosome replication)
Chromosome
replication
MITOSIS
Replicated
chromosome
Prophase
Chromosomes
align at the
metaphase plate
Sister chromatids
separate during
anaphase
Metaphase
Daughter
cells of
mitosis
Tetrad formed by
synapsis of replicated
homologous
chromosomes
Tetrads align at the
Homologous chromosomes
separate but sister
chromatids remain together
during anaphase I
No further chromosomal
replication; sister chromatids
anaphase II
Daughter cells of meiosis II
(usually gametes)
Prophase I
Metaphase I
Daughter cells
of meiosis I
Meiosis II
MEIOSIS
2n = 4 2n 2n n n n n

28. Figure 27.6 Meiosis (1 of 2). Interphase cell Centriole pairs Nuclear
envelope
Chromatin
Interphase events
As in mitosis, meiosis is
preceded by DNA replication and
other preparations for cell
division.
Prophase I
Prophase events occur, as in mitosis. Additionally,
synapsis occurs: Homologous chromosomes come
together along their length to form tetrads. During
synapsis, the “arms” of homologous chromatids wrap
around each other, forming several crossovers. The
nonsister chromatids trade segments at points of
crossover. Crossover is followed through the diagrams
below.
Anaphase I
Unlike anaphase of mitosis, the centromeres do not
separate during anaphase I of meiosis, so the sister
chromatids (dyads) remain firmly attached. However, the
homologous chromosomes do separate from each other
and the dyads move toward opposite poles of the cell.
Metaphase I
The tetrads align randomly on the spindle
equator in preparation for anaphase.
Crossover
Spindle
Sister
chromatids
Nuclear envelope
fragments late
in prophase I
Tetrad
Dyad
Centromere
MEIOSIS I
Telophase I
The nuclear envelopes re-form around the chromosomal
masses, the spindle breaks down, and the chromatin
reappears as telophase and cytokinesis are completed.
The 2 daughter cells (now haploid) enter a second
interphase-like period, called interkinesis, before
meiosis II occurs. There is no second replication of DNA
before meiosis II.
Chromosomes
uncoil
envelopes
re-form
Cleavage
furrow
2n = 4

29. Figure 27.6 Meiosis (2 of 2). MEIOSIS II Prophase II
Meiosis II begins with the
products of meiosis I (2
haploid daughter cells) and
undergoes a mitosis-like
nuclear division process
referred to as the equational
division of meiosis.
Prophase II
Metaphase II
After progressing through
the phases of meiosis and
cytokinesis, the product is 4
haploid cells, each
genetically different from the
original mother cell. (During
human spermatogenesis,
the daughter cells remain
interconnected by
cytoplasmic extensions
during the meiotic phases.)
Anaphase II
Telophase II
and cytokinesis
Products of
meiosis:
haploid
daughter cells

30. Processes of Spermatogenesis
Follicle stimulating hormone (FSH) regulates
Spermatogonia (stem cells) - rapid mitosis to produce more stem cells before puberty
First division of a stem cell becomes 1 stem cell & 1 primary spermatocyte
Primary spermatocytes undergo meiosis
Haploid spermatids

31. Figure 27.7b Spermatogenesis.

32. Figure 27.7c Spermatogenesis.
Basal lamina
Spermatogonium
(stem cell)
Cytoplasm of adjacent
sustentacular cells
Sustentacular
cell nucleus
Tight junction between
Lumen of
seminifer-
ous tubule
Late spermatids
Early
spermatids
Secondary
spermatocytes
Cytoplasmic
bridge
Primary
spermatocyte
Spermatozoa
Type B daughter cell
Type A daughter cell
remains at basal lamina
as a stem cell
(c) A portion of the seminiferous tublule wall, showing the spermato-
genic cells surrounded by sustentacular cells (colored gold)

33. Spermiogenesis Approximately 24 days Golgi apparatus Acrosomal vesicle
Mitochondria
Acrosome
Nucleus 1 2
Centrioles
Spermatid
nucleus
Microtubules
Midpiece
Head
(a) 3
Flagellum
Excess
cytoplasm 4
Tail 5 6 7
(b)
Figure 27.8a, b

34. Anatomy of a Mature Sperm Cell
Late spermatids - distinct regions
Head –DNA covered by acrosome
Midpiece
Tail
Sperm cells = mature spermatids
Spermatogenesis takes 64 to 72 days
Only human flagellated cell

35. Testosterone Production
- Most important hormone of testes
- Produced in interstitial cells
- Functions
Organ development
Sex drive
Secondary sex characteristics
Deepening of voice
Increased hair growth
Larger skeletal muscles
Thicker bones

36. Regulation of Male Androgens (Sex Hormones)