Male Reproductive System

What is the male reproductive system comprised of?

Testes

Ducts

Accessory glands

Penis

What is the function of the testes?

Produce spermatozoa and testosterone

Important in sexual differentiation

Where is gonadotropin secreted from?

The pituitary gland

What do metabolites stimulate in males during puberty?

Accessory glands

Hair follicles

What are the functional components of the system of ducts?

Ductuli efferentes → Epididymis → Vas deferens → Ejaculatory duct → Urethra

What are the functional components of the accessory (exocrine) glands?

Seminal vesicles (x2)

Prostate gland

What are the functional components of the penis?

Copulatory organ

Bulbourethral gland lubricate urethra

What covers the testes and divides them into lobules?

Tunica albuginea

• Dense irregular connective tissue capsule that forms septa creating ~250 lobules

What terminology is more accepted in the gross room?

Testis and Testes

What structures are found within each testicular lobule?

1-4 seminiferous tubules

Interstitial (Leydig) cells

Connective tissue

Describe seminiferous tubules

Highly coiled, 200 μm diameter, 30-70 cm long

Lined by germinal epithelium (Sertoli + spermatogenic cells)

Surrounded by myoid cells

What is this?

Posterior aspect of the testes

• TA - Tunica albuginea

• RT - Rete testis

• S - Septa

• E - Epididymis

What are germinal epithelium composed of?

Sertoli cells

Spermatogenic stem cells

What is spermatogenesis?

Production of male gametes (~70 days)

What is spermiogensis?

Maturation into motile spermatozoon

What are the key features and functions of Sertoli cells?

Tall columnar cells with prominent nucleolus

Activated by FSH

Support/Nourish germ cells

Form blood-testis barrier

Secrete inhibin, regulate Leydig cells

Phagocytose residual bodies

What is phagocytosis?

Excess cytoplasm digested by lysosomes during spermiogenesis

What is this?

Seminiferous tubules

What cells are present here?

Sertoli cells (ST)

What is the arrow pointing at?

Interstitial (Leydig) cells

What stimulates Leydig cells and what do they produce?

Stimulated by LH to produce testosterone

What histologic features identify Leydig cells?

Round nucleus, dispersed chromatin (1-2 nucleoli)

Eosinophilic cytoplasm

Reinke crystals (protein inclusions) ← Characteristic THOUGH RARE

What are the three intratesticular ducts?

Straight tubules

Rete testis

Efferent ductulus

What epithelium lines straight tubules?

Initially → Only Sertoli cells

Later → Simple cuboidal

Describe the rete testis

Plexiform network

Simple cuboidal epithelium with microvilli

Surrounded by vascular collagenous tissue with myoid cells

What does short straight tubules connect?

Loops of seminiferous tubules to rete testis

What are the key features of efferent ductules?

Tall ciliated columnar cells alternating with short non-ciliated cells

Contains brown pigment

Smooth muscle helps move non-motile sperm

What is this?

Rete testes

What is this?

Ductus efferens

What are the functions of the epididymis?

Sperm accumulation, storage, maturation

Development of motility (spermogenosis)

Smooth muscle increases distally (sympathetic nervous system) → Strong contraction during ejaculation

What epithelium lines the epididymis?

Tall pseudostratified columnar epithelium with long cilia

Describe the vas deferens histology

Thick muscular wall (3 layers)

Pseudostratified columnar epithelium

Sympathetically innervated

What is this?

Epididymis

What is this?

Ductus (Vas) deferens

What is this?

Ductus (Vas) deferens

What forms the ejaculatory duct?

Ampulla of vas deferens

Seminal vesicle duct

Joins urethra in prostate gland

What percentage of seminal fluid is produced by seminal vesicles?

~85%

What are the key histologic features of seminal vesicles?

Pseudostratified tall columnar epithelium

Secretory cells with lipid droplets

Brown lipofuscin granules

What is this?

Seminal vesicles

What is this?

Prostate gland

What is the arrow pointing at?

Corpora amylacea-inspissated secretions (prostate gland)

What is this?

Semen

What organ is this?

Penis

What is this?

Corpus spongiosum

What is this?

Erectile tissue

• S: Sinuses

• HA: Helicine arteries

What substances do seminal vesicles secrete?

Fructose

Fibrinogen

Vitamin C

Prostaglandins

What are the four zones of the prostate?

Peripheral zone — Most cancer

Central zone

Transitional zone — BPH

Anterior fibromuscular zone

What does the prostate secrete?

Citric acid and proteolytic enzymes that liquefies coagulated semen after it is deposited in vagina

What are corpora amylacea?

Inspissated secretions found in prostate glands

What is the ejaculatory ducts relationship to the urethra?

Posterior

What histologic change indicates prostate cancer?

Loss of basal cells and prominent nucleoli

What are the histological features of the prostate?

Tall pseudostratified columnar epithelium (secretory) with prominent round basal nuclei and pale-staining cytoplasm

Small flat basal cells at base of gland

What is semen composed of?

Spermatozoa + seminal fluid (seminal vesicles + prostate)

What percentage of sperm are normally abnormal?

~25%

What is capacitation?

Final maturation in female tract involving:

• Cholesterol removal

• Membrane reorganization

• Increase intracellular calcium

What are the three erectile bodies of the penis?

Two corpora cavernosa (dorsal)

One corpus spongiosum (ventral, surrounds urethra)

Describe corpus spongiosum histology

Erectile tissue with large irregular vascular channels and fibrocollagenous stroma

What causes erection?

Parasympathetic-mediated dilation of helicine arteries

Filling of vascular sinuses

Venous outflow restriction

What epithelium lines the prostatic urethra?

Transitional/Urothelium

What epithelium lines the membranous urethra?

Stratified or pseudostratified columnar epithelium

What epithelium lines the penile urethra?

Pseudostratified columnar epithelium

Surrounded by the corpus spongiosum

What epithelium lines the urethral meatus?

Stratified squamous epithelium

What lubricates the penile urethra?

Bulbourethral glands of Cowper

What is the order of the different urethras?

Prostatic → Membranous → Penile → Urethral meatus