1. Chapter 27— The Male Reproductive System

2. Ch. 27 Study Guide
Read pp of section 27.1 before prenatal hormones and sexual differentiation section; also read sections (pp )
Comprehend Terminology (those in bold)
Study-- Figure questions, Think About It questions, and Before You Go On (section-ending) questions
Do end-of-chapter questions:
Testing Your Recall— 2-20
True or False– 1-9
Testing Your Comprehension– 3, 4 2

3. Said an ovum one night to a sperm, “You’re a very attractive young germ. Come join me, my sweet, let our nuclei meet And in nine months we’ll both come to term.” --Isaac Asimov

4. 27. 2. Male Reproductive Anatomy— A
27.2. Male Reproductive Anatomy— A. The Spermatic Ducts and the Accessory Glands

5. § A. Sperm’s journey
Testes– sperm-producing organs; inside the scrotum (skin-covered sac)
Routes (spermatic ducts) the sperm travel: A-Testes  B-Efferent ductules  C-Epididymis  D-Ductus deferens  E-Ejaculatory duct  F-Urethra  Exterior
Fig b

6. Anterior/posterior view?
Urinary bladder
Ureter
2. Prostate gland
1. Seminal vesicle
3. Bulbourethral gland E F D
Penis C B A
Glans penis

7. § Spermatic Ducts Include--
Efferent ductules
12 small ciliated ducts collecting sperm from rete testes and transporting it to epididymis
Epididymis (head, body and tail)
6 m long coiled duct adhering to posterior of testis
site of sperm maturation and storage (fertile for 60 days)
Ductus (vas) deferens (peristalsis during orgasm)
muscular tube 45 cm long passing up from scrotum through inguinal canal to posterior surface of bladder
Ejaculatory duct
2 cm duct formed from ductus deferens and seminal vesicle and passing through prostate to empty into urethra
Fig. 27.9, 27.11

8. § Male Urethra
Three Regions: prostatic, membranous and penile urethra--- totals 20 cm long (Fig b)
Function
It serves both urinary and reproductive roles
It cannot pass urine and semen simultaneously

9. A B C Seminal vesicle Prostate gland Bulbourethral gland Ampulla
Ejaculatory duct A
Bulbourethral gland B
Ductus deferens
Efferent ductules
Testis
Epididymis C
27-9

10. § Accessory Glands-A
Sperm is supported by semen from accessory sex glands--
including the seminal vesicles, prostate gland, and bulbourethral glands

11. § Accessory Glands-B Seminal vesicles (paired) Prostate gland (single)
posterior to bladder
Yellowish alkaline secretion empties into ejaculatory duct; constitute 60% of the semen
Containing fructose, sugars, ascorbic acid, a coagulating enzyme, prostaglandins, proseminogelin
Prostate gland (single)
below bladder, surrounds urethra and ejaculatory duct; digital rectal examination
2 x 4 x 3 cm; thin, acidic milky secretion; 30% of the semen
Plays a role in activating sperm, containing citrate (a nutrient), serine protease

12. § Accessory Glands-C Bulbourethral glands (paired; Cowper’s glands)
near bulb of penis
empty into penile urethra
neutralize urine
lubricating fluid secreted during sexual arousal

13. 27. 2. Male Reproductive Anatomy— B
27.2. Male Reproductive Anatomy— B. The Scrotum & Testicular Thermoregulation

14. § Scrotum Perineum– Fig. 27.6 Pouch (scrotum) holding testes
divided into 2 compartments by ______ which is external marked by perineal raphe
Spermatic cords– paired structures consisting of layers of CT and muscle enclosing ductus deferens, blood and lymphatic vessels, and testicular nerves.
Location– each spermatic cord begins at the entrance to the In-________ canal
Fig. 27.7

15. Fig. 27.6--The male perineum
27-15

17. § Testicular Thermoregulation
Sperm cannot be produced at core body temperature (too warm):
1. pampiniform plexus = near testicular artery, a network of veins– forming countercurrent heat exchanger that cools arterial blood entering testis by 1-2 degree Celsius (Fig. 27.8)
When Cold:
2. cremaster muscle = pulls testes close to body when cold
3. dartos muscle--
Contracts and scrotum becomes taut
wrinkles skin reducing surface area of scrotum

19. 27.2. Male Reproductive Anatomy— C. Testes

20. § Testes (Fig a-b)-A
Dimension-- Oval organ; 3 cm (anterior to posterior) x 2.5 cm (wide) x 4 cm (long)
Each testis is surrounded by two tunics: (From outermost and moving in)
Its anterior and lateral surfaces are covered by tunica vaginalis
Tunica albuginea– testis itself has a white fibrous capsule

22. Review spermatic ducts 

23. § Testes (Fig a-b)-B
Septa divide testes into wedge-shaped lobules containing seminiferous tubules (where sperm are produced)
each tubule lined with a thick germinal epithelium (several layers of germ cells) for sperm production
Tall Sertoli (sustentacular) cells; function?
Between the seminiferous tubules are interstitial (Leydig) cells, the source of testosterone
Fig and X

24. See next slide for details of germ and sustentacular cells

25. Sertoli cell Lumen of seminiferous tubule
Stages of sperm maturation: 
Spermatozoon
Tight junctions --see next slide
Spermatids
Secondary
spermatocyte
Primary
spermatocyte
Sertoli cell
Spermatogonium

26. § Blood-testis barrier of testes
(Structures) Formed by tight junctions between sustentacular (Sertoli) cells -- separating sperm from blood and immune systems
(Functions) Prevents proteins and other large molecules in the blood and intercellular fluid from getting to the germ cells

27. § Blood circulation to/from the testis
Sperm’s transportation inside the testes--Seminiferous tubules drain into rete testis which is embedded in the capsule on the posterior side
Testicular arteries– arise from the abdominal aorta; low BP of testicular artery results in poor O2 supply
sperm develop very large __________ helping them also survive hypoxic environment of female reproductive tract
Pampiniform plexus of veins and then testicular veins-- the right one drains to inferior vena cava; the left one drains into the left renal vein

28. 27.2. Male Reproductive Anatomy— D. The Penis

29. § Penis (Fig , 27.12)
Internal root; visible (external)-- shaft, and glans
external portion 4 in. long when flaccid
skin over shaft loosely attached allows expansion
extends over glans as prepuce (foreskin)
3 cylindrical bodies of erectile tissue
corpus spongiosum (1) along ventral side of penis
encloses penile urethra
at distal end, fill the entire glans
corpora cavernosa (2)
On each side; separated by a median septum
Each is ensheathed in a fibrous tunica albuginea
diverge like arms of a Y
each arm, called crus, attaches to pubic arch covered with ischiocavernosus muscle

32. 27.3. Sperm and Semen— A. Spermatogenesis

33. § Spermatogenesis--A
Def. of spermatogenesis– The production of sperm cells through a series of mitotic and meiotic cell divisions
Location?
How long does it take?
Microscopic examination– two important cell types (see next slide)

34. § Spermatogenesis--B Two important cell types in seminiferous tubules
Germ cells–
In various stages of sperm development, such as spermatogonia, primary spermatocytes, secondary spermatocytes
Sustentacular (Sertoli) cells– these cells provide crucial support for spermatogenesis
Figure 27.15

36. § Spermatogenesis--C Three major stages— Mitotic proliferation—
Spermatogonia located in the outermost layer of the seminiferous tubule, outside the blood-testis barrier (BTB)
One of the daughter cells (Type A spermatogonium) remain at the outer edge of the tubule; importance?
The other daughter cell (Type B spermatogonium) starts moving toward lumen forming 4 identical primary spermatocytes (2N)

37. § Spermatogenesis--D Meiosis— Spermiogenesis—
Each primary spermatocyte (2N) must pass through BTB (tight junction) and ultimately yield 4 spermatids (1N)
Spermiogenesis—
Spermatids become extremely specialized and motile spermatozoa
Sperm travel lightly
Figure x&y, 27.16

38. A. B.
Meiosis C.

39. Spermatogenesis Stages: Chromosomes: Mitosis Meiosis Spermio- genesis
(diploid number;
single strands)
Spermatogonia
One daughter cell remains
at the outer edge of the
seminiferous tubule to
maintain the germ cell line
One daughter cell moves
toward the lumen to
produce spermatozoa
Mitosis
46; 2n
(diploid number;
single strands)
Primary
spermatocyte
46; 2n
(diploid number;
doubled strands)
First meiotic
division
Meiosis
Secondary
spermatocyte
23; n
(haploid number;
double strands)
Second meiotic
division
23; n
(haploid number;
single strands)
Spermatids
Spermio-
genesis
23; n
(haploid number;
Single strands)
Spermatozoa

40. Figure 27.16

41. 27.3. Sperm and Semen— B. Spermatozoon

42. § The Spermatozoon--A Two parts– the head and the tail
Head contains three structures:
A nucleus– with a haploid set of chromosomes
Acrosome– a lysosome vesicle in a thin cap; in the apical half of the head
Flagellar basal body– is nestled in an indentation at the basal end of the nucleus
Fig

44. § The Spermatozoon--B Two parts– the head and the tail
Tail contains three regions:
Midpiece– many large mitochondria coil around the axoneme (center of the sperm) and they provide the ATP needed for the tail
Principal piece– constitutes most of the tail and provides motility for the spermatozoon
Endpiece– axoneme only; the narrowest part of the sperm
Fig

45. Figure 27.17b

46. 27.3. Sperm and Semen— C. Semen

47. § Semen (2-5 ml)--A
Def.– milky white mixture of sperm and accessory gland secretions expelled during orgasm
Functions–
provides a transport medium and nutrients (fructose mainly and also citrate and sugars)
protects and activates the sperm
overall alkalinity helps neutralize the acid environment
prostaglandins– decrease the viscosity of mucus guarding the entry of the uterus

48. § Semen--B
The clotting enzyme from the prostate activates proseminogelin (from the seminal vesicles) into seminogelin
Seminogelin sticks to the walls of the vagina, ensuring the semen doe not drain back
20-30 minutes after ejaculation: serine protease of the prostatic fluid breaks down seminogelin and liquefies the semen (sperm now very active)

49. § Semen—C; Low sperm count?
2-5 ml semen per ejaculation
200 million sperm per ejaculation
million sperm per ml
Low sperm count is < 20 million sperm per ml of semen (less than the minimal jackpot of the Powerball)