1. General Anatomy of the Male Reproductive System

3. Male reproductive system
Testes – produce sperm and are essential
Scrotum
Epididymis
Vas deferens
Seminal vesicles
Ejaculatory ducts
Prostate Gland
Urethra
Penis

4. Male Reproductive System
Testes
Ovoid glands that are suspended in the scrotum
Attached to scrotal tissue and spermatic cords
Consist of many lobules ( in each testis)
Each lobule contains:
Seminiferous Tubules for spermatogenesis
Interstitial cells of Leydig that secrete testosterone.

5. Male Reproductive System
The testes are each surrounded by two protective coats (or tunics):
Tunica Vaginalis (outer Layer) extension of peritoneum
Tunica Albuginea (Inner Layer) extends between each of the lobules

6. Male Reproductive System
Sperm produced in the testes leave via the tubulus rectus that conveys them to a network of tubules on one side of each testis called the rete testis
From here the sperm are carried via efferent ducts to the epididymis.

7. Male Reproductive System
2. Scrotum
This literally means "pouch" or "sac"
It is a pouch of skin that is incompletely divided into left and right halves.
Each half houses one testis.
The appearance of the scrotum changes with temperature.
Eg. Cold (or sexual arousal) it appears shorter and quite wrinkled, because it is pulled closer to the body for warmth.
Eg. Heat, the skin is flaccid (loose) and the testes hang lower in the scrotum to keep them cool.

8. Male Reproductive System
The movement of the scrotum and testes helps to maintain intra scrotal and hence testicular temperature 93°
Movement of the scrotum is achieved by two groups of muscles:
Dartos Muscle which is a smooth muscle and causes shrinking of the scrotum
Cremaster Muscle with is skeletal muscle and it elevates the testes. It is attached to the internal oblique muscle of the trunk

9. 3. Epididymis
Highly folded duct approx 6m long, for the passage of sperm from the testis to the vas deferens.
It has 3 divisions:
Head: connected to the testes receiving immature sperm
Body
Tail: continuous with the vas deferens, contains smooth muscle and during ejaculation, contractions of the smooth muscle expel mature sperm into the vas deferens.
Sperm may be stored in the epididymis from 18 hrs - 20 days.
During this time the sperm mature, including becoming motile, so they can fertilize an ovum.
Epididymis is shaped like a comma

10. Male Reproductive System
4. Vas deferens
Short, fairly straight tube approx 45 cm long.
Ascends from the scrotum into the abdomen and passes over the bladder.
Tube cut in vasectomy
doesn’t effect erection or performance
Vas deferens stores the sperm.
sperm are mature & motile
the local accumulation of CO2 from the normal metabolism of the sperm causes the pH to become acidic.
under these conditions sperm lose their motility
on ejaculation, the alkaline seminal fluid will counteract the low pH and the sperm will become motile again.
At the posterior wall of the bladder the tubes expand to form "ampulla of the vas deferens" and join a duct from the seminal vesicles to form the "ejaculatory duct".

11. Male Reproductive System
5. Seminal Vesicles
2 glands behind prostate gland, size & shape of finger,
secretes viscous fluid = 60-70% of seminal fluid (nourish & energize sperm)
Also secrete fructose, citric acid, amino acids and Prostaglandins.

12. Male Reproductive System
6. Ejaculatory ducts
Short tubes that descend through the prostate gland and terminate in the urethra.
Formed by the union of the vas deferens and seminal vesicle ducts

13. Male Reproductive System
7. Prostate gland
Chestnut-sized gland below bladder.
Surrounds the ejaculatory duct and part of the urethra.
Secretes a thin liquid that is milky, alkaline and constitutes 30% of the seminal fluid volume
Responsible for raising the pH of the female vagina.
Provides lubrication during coitus
7. 5. Cowper’s Glands
below prostate, 2 pea-sized glands connect to urethra by ducts;
secrete thick, clear mucus before ejaculation (at tip of penis)
alkaline to protect sperm from acidic vagina.
Fluid has sperm! (Sperm in urethra > PREGNANT!!)

14. Male Reproductive System
8. Urethra
Tube cm long.
Conveys urine and sperm (at different times).
Three regions of urethra
Contains glands which secrete mucus to aid lubrication during intercourse.

15. Male Reproductive System
9. Penis
Copulatory organ of the external genitalia.
Contains 3 compartments of erectile tissue which are covered by a loose layer of skin.
Two "corpora cavernosa"
One "corpus spongiosum" which lies ventrally in the penis and houses the spongy urethra. Expands at the end of the penis into the "glans penis".
When aroused, inc. blood into penis, these compartments fill and expand
Leads to erect penis – compression of vessels prevents blood flow out.
aroused, blood into penis, vessels expand, corpora cavernosa & corpus spongiosum fill & expand > penis erect
compression of vessels prevents blood flow out of penis; Engorgement;

16. A penis, with foreskin retracted

17. Male Reproductive System
9. Penis continued
Erectile tissue is sponge-like containing venous sinuses surrounded by arteries and veins.
Upon sexual stimulation, the arteries dilate and the spaces (or caverns) fill with blood. As they fill, the erectile tissue becomes rigid and the penis becomes erect.
Two main functions of the penis:
Removal of urine via the urethra
Receipt and ejection of sperm and seminal fluid during copulation, again via the urethra.

18. Male Reproductive System
In uncircumcised males there is a structure that covers the end of the glans penis called the "prepuce or foreskin".
Its proposed functions include protection, lubrication of glans, part of sexual pleasure system.
uncircumcised circumcised

20. All length measurements were taken when the penises were erect, along the top of the penis, from the point where the top of the penile shaft meets the pubic area to the tip.

21. Male Anatomy & Physiology
Factors effecting size:
heredity, vasocongestion, cold air or water, fear, anxiety (penis draws closer to body & smaller size)
Erection – urethra/urinary duct closes so semen passes through (ejaculation)
Erection not always because of sexual excitement
REM sleep (dreaming)

22. Myths
Penis Size: related to masculinity, aggression, ability to “perform”, sexual attractiveness, virility.
Size of shoe predictive of penis size (not research based!).
Size not related to ability to have sexual intercourse or pleasure partner.
Small flaccid penis enlarges more with erection than larger flaccid penis.

23. The Ejaculate
Ejaculate volume is about 3 ml and ranges from 2 to 6 ml.
pH is 7.5, slightly basic to neutralize the acidity of the urethra and the vagina
Of the 3 ml of an ejaculate
About 0.2 ml, originates from the Cowper's gland
About 0.5 ml from the prostate gland
about 2 ml is secreted from the seminal vesicles

24. Reproductive Process Semen production Semen is combo of:
Seminal Fluid - ejaculated liquid with sperm
Function: nourish sperm, hospitable environment, transportation of sperm
Semen is combo of:
seminal vesicle fld., prostate gland fld., sperm mixed in the urethra during ejaculation.
Is thick & sticky (clotting factor in fluid)
Keeps the sperm together during transport then liquefies so sperm can swim out.
Color varies: opalescent (milky white), yellowish or grayish as ejaculate, then becomes clear as it liquefies.
1 tsp. (2-6 Milliliters) semen ejaculated = 200>500 million sperm

25. Review: Journey of the Sperm

26. interstitial
cells-
testosterone

27. sperm
production
in the
seminferous
tubules

28. sperm
storage
in the
epididymis

29. transport
in the
vas
deferens

30. ampulla -
storage

31. fluid from
the
seminal
vessicles
ejaculatory
duct

32. fluid from
the
prostate
gland

33. cowper’s
gland

34. Spinal reflex triggers nerve impulses to ducts, glands, muscles of reproductive system.
ejaculation

35. The Process
Orgasm:
Intense, pleasurable physical sensations & general release of tension accompanying ejaculation.
Does not always occur with ejaculation
Ejaculation not always occur with orgasm
Refractory Period - no erections/orgasms for varying time
factors = age, environment, individual
few minutes to few days - maybe chemical effects in brain
After orgasm > blood flow  , erection ,
“Blue Balls”
Intense arousal without orgasm > heaviness felt in testes. Not as painful as implied.
If discomfort continues - masturbation > ejaculate for release.

36. More info
When seminal vesicles are full, feedback signals to sperm (inhibin) production.
Extra sperm die and are absorbed by body

37. General Anatomy of the Male Reproductive System

38. Anatomy of the Male Reproductive System

39. Internal and external anatomy of the Testis
Pathway for Sperm
1. Seminiferous tubule
2. Straight tubule
3. Rete testis
4. Efferent duct
5. Ductus Epididymis
6. Ductus deferens

40. Histology of the Testis and Spermatogenesis

41. Steps of Spermatogenesis
Spermatids: Cells resulting from meiosis II, become spermatozoa

42. Organs involved in the Production of Semen
Seminal Fluid: Volume of a typical ejaculation is 2.5 –5.0ml with a sperm count of 50 –150 million sperm (under 20 million sperm is considered infertile), fluid is slightly alkaline at pH 7.2 –7.7.
Seminal Vesicles: Produce 60% of the volume of seminal fluid; SV’s produce an alkaline viscous fluid that contains: fructose, prostaglandins, and clotting proteins

43. Organs involved in the Production of Semen
Prostate Gland: Produce 25% of the volume of seminal fluid; This fluid is a milky, slightly acidic fluid that contains citric acid (for ATP production), acid phosphatase along with several other enzymes ( prostate-specific antigen PSA, pepsinogen, and lysozyme
Bulbo-urethral gland: produces alkaline mucus that help lubricate the urethra and the head of the penis
Ampulla of ductus deferens: releases up to 150 million sperm cells

44. The Male Sexual Response
Arousal: various erotic thoughts and physical stimulation triggers parasympathetic reflexes that cause an erection.
Erection: occurs when neurons release Nitric oxide at their synaptic endings.
NO causes smooth muscles of the penile arteries to relax, vessels dilate, blood flow to the erectile tissue increases . The vascular channels engorge with blood, resulting pressure causes the penis to become stiff.

45. The Male Sexual Response
During arousal increases in heart rate, blood pressure, skeletal muscle tone, and hyperventilation occur
Bulbourethral glands: continued stimulation causes the release of mucus from these glands, this mucus lubricates the penile urethra and the glans penis. These secretions can carry sperm.

46. The Male Sexual Response
Plateau stage: Changes that begin during arousal are sustained at an intense level, head of the penis increases in diameter and the testes swell due to vasocongestion.
Toward the end of the plateau stage, emission occurs.
Emission: sympathetic stimulation causes peristaltic contractions of the ampulla that push fluid and spermatozoa into the ejaculatory duct, peristaltic contractions of the seminal vesicles and the prostate push seminal fluid in the ejaculatory duct and the penile urethra.
Contraction of the internal urethral sphincter and the bladder occurs.

47. The Male Sexual Response
Ejaculation: Sympathetic stimulation of the ischiocavernosus and bulbospongiosus muscles causes powerful rhythmic contractions that push the semen out of the penile urethra.
Orgasm; intensely pleasurable sensations associated with ejaculation. Other physiological changes include pronounced increase in heart rate and blood pressure.

48. The Male Sexual Response
Resolution: Sense of profound relaxation- genital tissues, heart rate, blood pressure, breathing, and muscle tone return to normal.
During early period of resolution, males enter a refractory period during which a second ejaculation and orgasm are physiologically impossible.

49. Spermatogenesis
The final step in the development the spermatids formed from spermatogenesis become mature spermatozoa, or sperm.
The mature sperm cell has a head, midpiece, and tail. The head, also called the nuclear region, contains the 23 chromosomes surrounded by a nuclear membrane. The tip of the head is covered by an acrosome, which contains enzymes that help the sperm penetrate the female gamete. The midpiece, metabolic region, contains mitochondria that provide adenosine triphosphate (ATP). The tail, locomotor region, uses a typical flagellum for locomotion.
The final step in the development of sperm is called spermiogenesis. In this process, the spermatids formed from spermatogenesis become mature spermatozoa, or sperm.
The mature sperm cell has a head, midpiece, and tail. The head, also called the nuclear region, contains the 23 chromosomes surrounded by a nuclear membrane. The tip of the head is covered by an acrosome, which contains enzymes that help the sperm penetrate the female gamete. The midpiece, metabolic region, contains mitochondria that provide adenosine triphosphate (ATP). The tail, locomotor region, uses a typical flagellum for locomotion.
The sperm are released into the lumen of the seminiferous tubule and leave the testes. They then enter the epididymis where they undergo their final maturation and become capable of fertilizing a female gamete.
Sperm production begins at puberty and continues throughout the life of a male. The entire process, beginning with a primary spermatocyte, takes about 74 days. After ejaculation, the sperm can live for about 48 hours in the female reproductive tract.

52. Spermatogenesis
The sperm are released into the lumen of the seminiferous tubule and leave the testes. They then enter the epididymis where they undergo their final maturation and become capable of fertilizing a female gamete.
Sperm production begins at puberty and continues throughout the life of a male.
The entire process, beginning with a primary spermatocyte, takes about 74 days. After ejaculation, the sperm can live for about 48 hours in the female reproductive tract.