Anatomy- Final Male Reproductive SG

What are the functions of the male reproductive system?

• Produces male gametes (sperm)

• Secretes hormones (mainly testosterone)

• Transports sperm from testes → penis

What structures are in the external male genitalia (in the perineum)?

• Penis

• Scrotum

What structures are located in the internal male genitalia?

• Testes (gonads)

• Epididymis

• Ductus (vas) deferens

• Ejaculatory duct

• Spongy (penile) urethra

• Seminal glands (vesicles)

• Prostate gland

• Bulbo-urethral glands

What are some additional structures of the male reproductive system that are not mentioned in the internal/external genitalia components?

• Glans penis

• Corpus cavernosum

• Corpus spongiosum

• Ampulla of ductus deferens

• Ureter

• Urinary bladder

How is the male reproductive system connected to the urinary system?

Urethra serves dual function (urine + semen)

What is the embryological development of the male reproductive system?

• Reproductive system develops high in abdomen

• Urinary system develops lower

• Structures change position during development

Testes Descent

• Move from dorsal abdominal wall → scrotum

• Travel through inguinal canal

• End in scrotal sac

Important Concepts

• Male system descends farther than female

• Kidneys migrate cranially (upward)

• Explains long spermatic cord pathway

Duct Development

• Mesonephric ducts → male genital ducts

• Paramesonephric ducts → female ducts

• In males: paramesonephric ducts degenerate

What are the facts and functions of the testes?

Basic Facts

• Located in scrotum (outside body)

• Size:

  • ~5 cm long

  • ~3 cm wide

  • ~2.5 cm thick

  • ~10–15 g

Functions

• Exocrine: produce sperm

• Endocrine: produce testosterone

Why do the testes descend?

• Testes develop at body temperature (~98.6°F)

• Sperm production requires lower temp (~96.6°F)

• Therefore must be outside body

What does the spermatic cord contain?

• Ductus deferens

• Blood vessels (testicular artery/vein)

• Lymphatics

• Nerves (ilioinguinal, genitofemoral)

• Cremaster Muscle

What is the anatomy of the scrotum?

Layers:

• Skin

• Dartos muscle

• Superficial fascia

• Cremaster muscle

• Tunica vaginalis (parietal & visceral layers)

Structures:

• Scrotal septum

• Perineal raphe

What is the internal structures of testes?

• Testes divided into lobules by septa

• Each lobule contains seminiferous tubules

In the male reproductive system, what is the pathway of sperm?

1. Seminiferous tubules

2. Straight tubules

3. Rete testis

4. Efferent ductules

5. Epididymis

What are the 2 cell types found in the testes and their locations & functions?

Sertoli Cells (Nurse Cells)

• Located inside seminiferous tubules

• Provide nutrients

• Support sperm development

Leydig Cells (Interstitial Cells)

• Located between tubules

• Produce testosterone

What are the functions of testosterone?

• Stimulates spermatogenesis

• Promotes sperm maturation

• Maintains accessory glands

• Develops secondary sex characteristics

• Stimulates growth

• Influences sexual behavior/drive

What are the structure, functions, and capacitation of the epididymis?

Structure

• Head → Body → Tail

Functions

• Receives sperm from efferent ducts

• Stores sperm (~2 weeks)

• Recycles damaged sperm

• Monitors fluid composition

• Site of sperm maturation

Capacitation

• Sperm become:

  • Motile (with seminal gland secretions)

  • Able to fertilize (in female tract)

What is the pathway for the ductus deferens (vas deferens)?

• Starts at epididymis tail

• Travels through inguinal canal

• Loops around bladder & ureter

• Expands into ampulla

• Forms ejaculatory duct → enters prostate

Why does the male urethra carry three different names and what are they

Because it passes through different regions:

1. Prostatic urethra

   • Through prostate

2. Membranous urethra

   • Between prostate & penis

3. Spongy (penile) urethra

   • Through penis

What are the 3 accessory glands found in the male reproductive system?

• Seminal Glands (vesicles)

• Prostate Gland

• Bulbo-Urethral Glands

What are the characteristics of the seminal glands?

• Produce 60% of semen

• Contents:

  • Fructose (energy)

  • Prostaglandins

  • Clotting factors

• Empty into ductus deferens

What are the characteristics of the prostate glands?

• Produces 20–30% of semen

• Secretions:

  • Slightly acidic

  • Contains seminalplasmin (antibiotic)

• Helps prevent UTIs

What are the characteristics of the bulbo-urethral glands?

• Produce ~5% of semen

• Secrete:

  • Thick, alkaline mucus

• Functions:

  • Neutralizes acidic urine residue

  • Lubricates urethra/penis

What are the composition and functions of semen?

• Volume per ejaculation: 2–5 mL

• Sperm count: 20–100 million/mL

Composition

• 60% seminal vesicles

• 30% prostate

• 5% bulbo-urethral glands

• 5% epididymis

Functions

• Nourishes sperm

• Dissolves vaginal mucus

• Antibacterial action

What is the anatomy of a penis?

Regions

• Root (attached to ischia)

• Body (shaft)

• Glans (distal end)

Erectile Tissue

• 2 × corpora cavernosa

• 1 × corpus spongiosum (contains urethra)

Additional Structures

• Crus (attached to ischium)

• Deep artery of penis

In the male reproductive system, how long is the development and puberty stage?

• Testes descend within 1st year of life

• Puberty:

  • Boys: ~9–14 years

  • Early: ≤8 years 

How common is an inguinal hernia for males vs females?

• More common in males (1 in 5)

• Females (1 in 50)

How is ejaculation controlled?

• Controlled by sympathetic nerves

• Causes peristalsis in:

  • Ductus deferens

  • Seminal glands

  • Prostate

  • Bulbo-urethral glands

→ Leads to semen release

What type of nerve controls an erection?

Parasympathetic Nerves

What is the process for an erection?

• Smooth muscle relaxes

• Arteries dilate

• Blood fills erectile tissue

• → erection

What is the function of the testes?

Produce sperm (spermatogenesis) and secrete testosterone.

How is a testis organized?

Surrounded by tunica albuginea → divided into lobules → each contains seminiferous tubules → lead to rete testis → efferent ductules.

What roles do the accessory glands of the male reproductive system play?

They produce seminal fluid to nourish, protect, and transport sperm.

• Seminal vesicles: fructose (energy)

• Prostate: enzymes (activate sperm)

• Bulbourethral glands: mucus (lubrication, neutralization)

What is the ductus deferens (structural & functional) and what is its course in the body?

A thick, muscular tube that transports sperm via peristalsis.

Course: Epididymis → spermatic cord → inguinal canal → pelvic cavity → joins seminal vesicle → forms ejaculatory duct

Trace the pathway of sperm from their origin to ejaculation?

Seminiferous tubules → rete testis → efferent ductules → epididymis → ductus deferens → ejaculatory duct → urethra → out.

What are the functions of the cavernous bodies?

Fill with blood to produce erection (corpus cavernosum and corpus spongiosum).

Can you describe the integration of the urinary system and reproductive system in males?

They share the urethra; urine and semen are kept separate by sphincters, and urine flow is blocked during ejaculation.

What is ejaculate comprised of?

Sperm (~5%) + seminal vesicle fluid (~60%) + prostate fluid (~30%) + small bulbourethral secretions.

Where is the epididymis, what are its regions, and what is its function?

Located on posterior testis; regions = head, body, tail; function = sperm maturation, storage, and motility.

How does the male reproductive system develop embryologically?

From intermediate mesoderm; Y chromosome (SRY gene) and testosterone drive male development; Wolffian ducts form male structures.

What is the route of the testis from its earliest embryological position to its adult position?

Starts near kidneys → descends through inguinal canal → into scrotum (guided by gubernaculum).

What are the differing temperature needs of the testis?

Needs ~34–35°C; regulated by dartos muscle, cremaster muscle, and pampiniform plexus.