intermingled smooth muscle for sympathetic controlled contraction
How is the prostate histologically stained?
Stained using a Prostate Specific Antigen-specific stain which appears brown under LM
Compare benign prostate hyperplasia and prostate carcinoma.
Benign: increased epl proliferation, cells remain polarized, still testosterone dependent
Carcinoma (malignant): increase epl proliferation, not polarized, no lumen (appears endocrine instead of exocrine), PSA is released into the stroma and fenestrated capillaries, testosterone-independent
What is the functional role of the urethra?
Common urine/semen passage
Describe the epithelial transitions in the urethra.
Begins as transitional epl (expansion/contraction) in the prostatic urethra. Then it becomes pseudostratified columnar epithelium (some mucous secretion) in the membranous/bulbar urethra. Finally it becomes stratified squamous epl (protective, merges with skin externally) in the penile urethra.
Since the transition is gradual, there is a lower likelihood of tumour development, and it is protective of infection.
Describe the structure of the penis.
Three columns of erectile tissue = corpora (corpus spongiosum and 2 corpora cavernosum)
Tissue of corpora is fibroelastic CT
Each corpus is surrounded by a dense irregular CT capsule (tunica albuginea)
Highly vascular- helicine arteries with prominent smooth muscle
Corpora contain venous spaces/sinuses
Compare the flaccid and erect state of erectile tissue.
1) helicine arterial smooth muscle contracted
2) little blood to venous sinuses in corpora
3) considerable blood shunted directly to non-corporal veins via arteriovenous anastomses (direct path from artery to vein without a capillary bed)
1) Helicine arterial smooth muscle relaxed
2) Increased blood to venous sinuses which fill and expand
3) Decreased drainage to veins from venous sinuses due to pressure against the tunica albuginea (maintains erection)
Name the signals/messengers involved in facilitating erection.