Pathology of the male reproductive tract Flashcards
What is the structure and function of the scrotum and its contents (testes, epididymis, vaginal tunics and espermatic cord)?
Produce spermatozoa and hormones, especially testosterone
What is the structure and function of the accessory glands of the male repro tract?
Produce ejaculatory fluid to support, nourish, and protect spermatozoa
What is the structure and function of the penis and prepuce?
Enter the vagina of the female and deposit the ejaculate
What are the portals of entry into the male reproductive tract?
- Direct penetration
- Ascending infection
- Hematogenous spread
- Peritoneal spread
What are the defence mechanisms of the male repro tract?
- Vulnerability to injury high antigenicity of spermatozoa and the long and narrow duct system
- Isolation for protection and prevention epithelial barrier
- Pattern recognition molecules, soluble factors, continuous flushing, rapid recruitment of inflammatory cells
- Blood testis barrier spermatozoa as foreign to the body
- Reduced immune responsiveness in the testes immunotolerance
How does the scrotum (and its contents) respond to injury?
o Germ cell degeneration, death, and depletion
o Sertoli cells: swelling and vacuolation
o Injury to Leydig cells: ceases production of testosterone, impacting on spermatogenesis (increasing apoptosis and by inhibiting maturation of spermatids)
o Testicular compensatory hypertrophy
o Epididymis: severe injury leads to spermiostasis and potential rupture
How do the accessory glands respond to injury?
Injury not common. It can lead to reduced function usually, but fertility is maintained
How does the penis and prepuce respond to injury?
Excessive swelling or fibrosis may lead to stenosis and prevent penis extrusion
What conditions can occur in the scrotal skin?
Susceptible to the same conditions as normal skin
- Dermatitis
- vascular disurbances
- skin tumours
- testicular tumours
What conditions can occur in the vaginal tunic?
Susceptible to the same conditions as the peritoneum
- Hydrocele and haematocele
- Disorders of growth
o Mesothelioma and carcinoid
- Inflammation
o Trauma or local infection
o Adhesion: fibrinous and fibrous (limit the movement of the testes and alter its ability to thermoregulate)
What conditions can occur in the testes and epididymis?
Degeneration -> testicular degeneration and atrophy
Inflammation -> orchitis, epididymitis
Disorders of growth -> testicular neoplasia, interstitial cell tumours, seminoma germ cells, teratomas
Explain testicular degeneration and atrophy
- Uni - (local event) or bilateral (systemic problem)
- In young animals, difficult to differentiate from hypoplasia morphologically
- Major causes include: fever; local inflammation; nutritional deficiencies; ischaemia; obstruction; radiation and therapeutic drugs (amphotericin B, gentamicin, and chemotherapy); hormonal imbalance and senility
- Grossly: reduced in size and firm, areas of mineralization may be present
- Microscopically: decreased numbers of germinal cells, vacuolated Sertoli cells, intratubular multinucleated spermatids, and interstitial fibrosis
What is orchitis?
- Inflammatory condition
- Less common than (but usually associated to) epididymitis
- Primary orchitis usually caused by haematogenous infection (Ex.: Brucella species and Corynebacterium
- Anti-inflammatory environment
- Spermatic granulomas may form
- Lymphocytic non suppurative orchitis may be associated to infertile animals
- Intratubular (most likely ascending and associated to epididymitis)
- Interstitial (usually incidental)
- Necrotizing (Ex.: Brucella species, FIP, severe trauma, ischaemia)
- Granulomatous (Ex: Mycobacteria or fungal infections)
What is epididymitis?
- Inflammatory condition
Epididymal enlargement
Important in rams and dogs, bur rare in other species
Any inflammation has the potential to cause obstruction of spermatozoal flow and spermatic granuloma
Usually unilateral and followed by periorchitis
Acute
• Gross: swollen and soft
• Microscopically: bacteria and neutrophils in the lumen, oedema, fibrin exudation, necrosis, extravasation of spermatozoa
Chronic
• Gross: firm, spermatic granulomas
• Microscopically: neutrophils and macrophages in the lumen, epithelial hyperplasia, lymphocytes and plasma cells in the interstitium
It may cause testicular degeneration
Fibrinous or fibrous adhesions between vaginal tunics
Explain the 4 neoplasms that can arise in the testes
Sustentacular (sertoli) cell tumours
Interstitial (leydig) cell tumours
Seminoma germ cells
Teratomas
Why would atrophy or metaplasia occur in the prostate?
- Atrophy occurs in any condition in which there is cessation of androgen stimulation
- Squamous metaplasia occurs with chronic irritation or increased estrogen stimulation
What is it called when the prostate is enlarged due to an inflammatory condition?
Prostatitis
o Can be an important disease in dogs usually bacterial (commonly normal flora of skin or lower urinary tract)
Common in ageing entire dogs
o Clinically important when there is toxaemia or urinary obstruction
o Usually together with hyperplasia Acute: ascending bacteria from urethra
o Chronic: unresolved acute lesions
o Abscess formation and replacement with fibrous tissue
o Important site for persistence of Brucella
Explain benign prostatic hyperplasia
Common in ageing entire dogs
Hormone related castration is therapeutic
Usually relatively regular bilateral enlargement palpable rectally
May be cystic
Most are asymptomatic
Clinical signs usually restricted to constipation but can involve stranguria and haematuria
Increased prevalence of urogenital tract infection
Explain prostatic neoplasia - adenocarcinoma
Relatively uncommon in dogs and rare inother species
It is unclear in dogs whether prostatic neoplasia is related to hormonal environment
Metastasis to urinary bladder, iliac lymph nodes, pelvis and lungs
Irregular enlarged prostate on rectal palpation
